Ages – Hard Level Questions – UGC NET Paper 1

Q1): 6 years ago, a father was 5 times as old as his son. After 6 years, the father will be 3 times as old as the son. Find the father’s present age.
A) 60 years
B) 63 years
C) 66 years
D) 69 years

Answer: C) 66 years

Explanation:

  • Step 1: Let son’s present age = S, father’s present age = F
  • Step 2: 6 years ago: F − 6 = 5(S − 6)
  • Step 3: So F = 5S − 24
  • Step 4: After 6 years: F + 6 = 3(S + 6) ⇒ F = 3S + 12
  • Step 5: 5S − 24 = 3S + 12 ⇒ 2S = 36 ⇒ S = 18
  • Final: F = 3S + 12 = 3×18 + 12 = 66, so option C is correct

Q2): 8 years ago, a mother was 6 times as old as her daughter. After 4 years, the mother will be 3 times as old as the daughter. Find the daughter’s present age.
A) 14 years
B) 15 years
C) 16 years
D) 17 years

Answer: C) 16 years

Explanation:

  • Step 1: Let daughter’s present age = D, mother’s present age = M
  • Step 2: 8 years ago: M − 8 = 6(D − 8) ⇒ M = 6D − 40
  • Step 3: After 4 years: M + 4 = 3(D + 4) ⇒ M = 3D + 8
  • Step 4: 6D − 40 = 3D + 8 ⇒ 3D = 48 ⇒ D = 16
  • Final: Daughter’s present age is 16, so option C is correct

Q3): 9 years ago, the ages of A and B were in the ratio 2 : 3. After 6 years, their ages will be in the ratio 3 : 4. Find A’s present age.
A) 36 years
B) 38 years
C) 39 years
D) 42 years

Answer: C) 39 years

Explanation:

  • Step 1: Let present ages be A = x and B = y
  • Step 2: 9 years ago ratio: (x − 9)/(y − 9) = 2/3
  • Step 3: Cross-multiply: 3(x − 9) = 2(y − 9) ⇒ 3x − 27 = 2y − 18 ⇒ 3x = 2y + 9
  • Step 4: After 6 years ratio: (x + 6)/(y + 6) = 3/4
  • Step 5: 4(x + 6) = 3(y + 6) ⇒ 4x + 24 = 3y + 18 ⇒ 4x = 3y − 6
  • Step 6: Solve the two equations ⇒ x = 39, y = 54
  • Final: A’s present age is 39 years, so option C is correct

Q4): The present ages of A and B are in the ratio 7 : 9. Their age difference is 12 years. After how many years will their ages be in the ratio 4 : 5?
A) 4 years
B) 6 years
C) 8 years
D) 10 years

Answer: B) 6 years

Explanation:

  • Step 1: Let present ages be 7k and 9k
  • Step 2: Difference = 9k − 7k = 2k = 12 ⇒ k = 6
  • Step 3: So A = 42 and B = 54
  • Step 4: After t years: (42 + t)/(54 + t) = 4/5
  • Step 5: 5(42 + t) = 4(54 + t) ⇒ 210 + 5t = 216 + 4t ⇒ t = 6
  • Final: After 6 years ratio becomes 4:5, so option B is correct

Q5): 6 years ago, the ages of A and B were in the ratio 3 : 5. After 6 years, their ages will be in the ratio 5 : 7. Find A’s present age.
A) 22 years
B) 24 years
C) 26 years
D) 28 years

Answer: B) 24 years

Explanation:

  • Step 1: Let present ages be A = x and B = y
  • Step 2: 6 years ago: (x − 6)/(y − 6) = 3/5
  • Step 3: 5(x − 6) = 3(y − 6) ⇒ 5x − 30 = 3y − 18 ⇒ 5x = 3y + 12
  • Step 4: After 6 years: (x + 6)/(y + 6) = 5/7
  • Step 5: 7(x + 6) = 5(y + 6) ⇒ 7x + 42 = 5y + 30 ⇒ 7x = 5y − 12
  • Step 6: Solve ⇒ x = 24 and y = 36
  • Final: A’s present age is 24 years, so option B is correct

Q6): The present ages of A, B, and C are in the ratio 3 : 5 : 6. After 6 years, C’s age will be equal to the sum of A’s and B’s ages 6 years ago. Find C’s present age.
A) 48 years
B) 51 years
C) 54 years
D) 57 years

Answer: C) 54 years

Explanation:

  • Step 1: Let present ages be A = 3k, B = 5k, C = 6k
  • Step 2: After 6 years: C becomes 6k + 6
  • Step 3: 6 years ago: A was 3k − 6 and B was 5k − 6
  • Step 4: Given 6k + 6 = (3k − 6) + (5k − 6)
  • Step 5: 6k + 6 = 8k − 12 ⇒ 2k = 18 ⇒ k = 9
  • Final: C = 6k = 54 years, so option C is correct

Q7): Average age of A, B, and C is 24 years. Average age of B, C, and D is 28 years. Average of A and D is 30 years. If B is 6 years older than C, find C’s present age.
A) 19 years
B) 20 years
C) 21 years
D) 22 years

Answer: C) 21 years

Explanation:

  • Step 1: From average: A + B + C = 24×3 = 72
  • Step 2: From average: B + C + D = 28×3 = 84
  • Step 3: Subtract Step 1 from Step 2: D − A = 12
  • Step 4: From average of A and D: A + D = 30×2 = 60
  • Step 5: Solve: (A + D) and (D − A) ⇒ D = 36, A = 24
  • Step 6: Now B + C = 72 − A = 72 − 24 = 48 and B = C + 6
  • Step 7: (C + 6) + C = 48 ⇒ 2C = 42 ⇒ C = 21
  • Final: C’s present age is 21 years, so option C is correct

Q8): A’s present age is equal to B’s age 6 years ago. After 6 years, the sum of their ages will be 72 years. Find A’s present age.
A) 24 years
B) 26 years
C) 27 years
D) 28 years

Answer: C) 27 years

Explanation:

  • Step 1: Let present ages be A = x and B = y
  • Step 2: Given x = y − 6
  • Step 3: After 6 years: (x + 6) + (y + 6) = 72
  • Step 4: So x + y + 12 = 72 ⇒ x + y = 60
  • Step 5: Substitute x = y − 6 ⇒ (y − 6) + y = 60 ⇒ 2y = 66 ⇒ y = 33
  • Final: x = y − 6 = 27, so option C is correct

Q9): The present ages of A and B are in the ratio 5 : 7. A’s age after 8 years will be equal to B’s age 6 years ago. Find B’s present age.
A) 45 years
B) 47 years
C) 49 years
D) 51 years

Answer: C) 49 years

Explanation:

  • Step 1: Let present ages be A = 5k and B = 7k
  • Step 2: Condition: A + 8 = B − 6
  • Step 3: So 5k + 8 = 7k − 6
  • Step 4: 14 = 2k ⇒ k = 7
  • Final: B = 7k = 49 years, so option C is correct

Q10): At present, A’s age is ( \frac{4}{5} ) of B’s age. After 10 years, A’s age will be ( \frac{5}{6} ) of B’s age. Find A’s present age.
A) 36 years
B) 38 years
C) 40 years
D) 42 years

Answer: C) 40 years

Explanation:

  • Step 1: Let B’s present age = B
  • Step 2: Given A = (4/5)B
  • Step 3: After 10 years: A + 10 = (5/6)(B + 10)
  • Step 4: Substitute A: (4/5)B + 10 = (5/6)(B + 10)
  • Step 5: Multiply by 30: 24B + 300 = 25B + 250 ⇒ B = 50
  • Final: A = (4/5)×50 = 40, so option C is correct

Q11): The sum of present ages of A and B is 66 years. B is 18 years older than A. After how many years will B be ( \frac{3}{2} ) of A?
A) 10 years
B) 11 years
C) 12 years
D) 13 years

Answer: C) 12 years

Explanation:

  • Step 1: Let A = x, then B = x + 18
  • Step 2: Given x + (x + 18) = 66 ⇒ 2x = 48 ⇒ x = 24
  • Step 3: So A = 24 and B = 42
  • Step 4: After t years: 42 + t = (3/2)(24 + t)
  • Step 5: 2(42 + t) = 3(24 + t) ⇒ 84 + 2t = 72 + 3t ⇒ t = 12
  • Final: After 12 years condition holds, so option C is correct

Q12): The sum of present ages of A, B, and C is 100 years. 4 years ago, A : B = 1 : 2. After 5 years, B : C = 3 : 4. Find C’s present age.
A) 45 years
B) 46 years
C) 47 years
D) 48 years

Answer: C) 47 years

Explanation:

  • Step 1: Let present ages be A = a, B = b, C = c with a + b + c = 100
  • Step 2: 4 years ago ratio: (a − 4)/(b − 4) = 1/2 ⇒ 2(a − 4) = (b − 4) ⇒ b = 2a − 4
  • Step 3: After 5 years ratio: (b + 5)/(c + 5) = 3/4 ⇒ 4(b + 5) = 3(c + 5)
  • Step 4: 4b + 20 = 3c + 15 ⇒ 3c = 4b + 5 ⇒ c = (4b + 5)/3
  • Step 5: Take a = 19 ⇒ b = 2(19) − 4 = 34 ⇒ c = (4×34 + 5)/3 = 141/3 = 47
  • Step 6: Check sum: 19 + 34 + 47 = 100 (fits)
  • Final: C’s present age is 47 years, so option C is correct

Q13): A father is 28 years older than his son. A grandfather is 26 years older than the father. After 6 years, grandfather will be 3 times the son’s age. Find the father’s present age.
A) 47 years
B) 48 years
C) 49 years
D) 50 years

Answer: C) 49 years

Explanation:

  • Step 1: Let son’s present age = S
  • Step 2: Father’s present age = S + 28
  • Step 3: Grandfather’s present age = (S + 28) + 26 = S + 54
  • Step 4: After 6 years: grandfather = S + 60 and son = S + 6
  • Step 5: Given S + 60 = 3(S + 6) ⇒ S + 60 = 3S + 18
  • Step 6: 42 = 2S ⇒ S = 21
  • Final: Father = S + 28 = 21 + 28 = 49, so option C is correct

Q14): 8 years ago, the ages of A and B were in the ratio 3 : 4. After 12 years, their ages will be in the ratio 5 : 6. Find B’s present age.
A) 46 years
B) 47 years
C) 48 years
D) 49 years

Answer: C) 48 years

Explanation:

  • Step 1: Let present ages be A = x and B = y
  • Step 2: 8 years ago: (x − 8)/(y − 8) = 3/4
  • Step 3: 4(x − 8) = 3(y − 8) ⇒ 4x − 32 = 3y − 24 ⇒ 4x = 3y + 8
  • Step 4: After 12 years: (x + 12)/(y + 12) = 5/6
  • Step 5: 6(x + 12) = 5(y + 12) ⇒ 6x + 72 = 5y + 60 ⇒ 6x = 5y − 12
  • Step 6: Solve the two equations ⇒ y = 48
  • Final: B’s present age is 48 years, so option C is correct

Q15): The present ages of A and B are in the ratio 5 : 6. After 7 years, their ages will be in the ratio 11 : 13. Find A’s present age.
A) 68 years
B) 70 years
C) 72 years
D) 74 years

Answer: B) 70 years

Explanation:

  • Step 1: Let present ages be A = 5k and B = 6k
  • Step 2: After 7 years: (5k + 7)/(6k + 7) = 11/13
  • Step 3: 13(5k + 7) = 11(6k + 7)
  • Step 4: 65k + 91 = 66k + 77
  • Step 5: k = 14
  • Final: A = 5k = 5×14 = 70, so option B is correct

Q16): Average age of A, B, and C is 28 years. Average age of B, C, and D is 32 years. If A : D = 3 : 5, find the average age of B and C.
A) 31 years
B) 32 years
C) 33 years
D) 34 years

Answer: C) 33 years

Explanation:

  • Step 1: From average: A + B + C = 28×3 = 84
  • Step 2: From average: B + C + D = 32×3 = 96
  • Step 3: Subtract Step 1 from Step 2: D − A = 12
  • Step 4: Given A : D = 3 : 5 ⇒ let A = 3k and D = 5k
  • Step 5: Then D − A = 2k = 12 ⇒ k = 6 ⇒ A = 18, D = 30
  • Step 6: B + C = 84 − A = 84 − 18 = 66
  • Final: Average of B and C = (B + C)/2 = 66/2 = 33, so option C is correct

Q17): A is 4 years less than 3 times B. After 5 years, A will be twice B (at that time). Find A’s present age.
A) 21 years
B) 22 years
C) 23 years
D) 24 years

Answer: C) 23 years

Explanation:

  • Step 1: Let B’s present age = b
  • Step 2: Given A = 3b − 4
  • Step 3: After 5 years: A + 5 = 2(B + 5)
  • Step 4: Substitute A: (3b − 4) + 5 = 2(b + 5)
  • Step 5: 3b + 1 = 2b + 10 ⇒ b = 9
  • Final: A = 3b − 4 = 27 − 4 = 23, so option C is correct

Q18): The present ages of A and B are in the ratio 3 : 4 and their sum is 70 years. After how many years will their ages be in the ratio 5 : 6?
A) 18 years
B) 19 years
C) 20 years
D) 21 years

Answer: C) 20 years

Explanation:

  • Step 1: Let present ages be 3k and 4k
  • Step 2: Given 3k + 4k = 70 ⇒ 7k = 70 ⇒ k = 10
  • Step 3: So A = 30 and B = 40
  • Step 4: After t years: (30 + t)/(40 + t) = 5/6
  • Step 5: 6(30 + t) = 5(40 + t) ⇒ 180 + 6t = 200 + 5t ⇒ t = 20
  • Final: After 20 years ratio becomes 5:6, so option C is correct

Q19): 5 years ago, the ages of A and B were in the ratio 3 : 5. After 8 years, their ages will be in the ratio 2 : 3. Find B’s present age.
A) 66 years
B) 68 years
C) 70 years
D) 72 years

Answer: C) 70 years

Explanation:

  • Step 1: Let present ages be A = x and B = y
  • Step 2: 5 years ago: (x − 5)/(y − 5) = 3/5
  • Step 3: 5(x − 5) = 3(y − 5) ⇒ 5x − 25 = 3y − 15 ⇒ 5x = 3y + 10
  • Step 4: After 8 years: (x + 8)/(y + 8) = 2/3
  • Step 5: 3(x + 8) = 2(y + 8) ⇒ 3x + 24 = 2y + 16 ⇒ 3x = 2y − 8
  • Step 6: Solve ⇒ y = 70
  • Final: B’s present age is 70 years, so option C is correct

Q20): A is 5 years younger than C, and B is 5 years older than C. If A : B = 6 : 7, after how many years will A : B become 9 : 10?
A) 25 years
B) 28 years
C) 30 years
D) 32 years

Answer: C) 30 years

Explanation:

  • Step 1: Let C’s present age = c
  • Step 2: Then A = c − 5 and B = c + 5
  • Step 3: Given (c − 5)/(c + 5) = 6/7
  • Step 4: 7(c − 5) = 6(c + 5) ⇒ 7c − 35 = 6c + 30 ⇒ c = 65
  • Step 5: So A = 60 and B = 70
  • Step 6: After t years: (60 + t)/(70 + t) = 9/10 ⇒ 10(60 + t) = 9(70 + t)
  • Step 7: 600 + 10t = 630 + 9t ⇒ t = 30
  • Final: After 30 years ratio becomes 9:10, so option C is correct

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