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In a family, the age of father, mother, son, and grandson are A, B, C, and D respectively. Given that A - B = 3, B + C = 78, C + D = 33 and the average age of the family is 34 years, then (B - C) is:
  • a)
    19
  • b)
    20
  • c)
    21
  • d)
    22
Correct answer is option 'D'. Can you explain this answer?
Most Upvoted Answer
In a family, the age of father, mother, son, and grandson are A, B, C,...
Given information:
- Age of father = A
- Age of mother = B
- Age of son = C
- Age of grandson = D
- A - B = 3
- B * C = 78
- C * D = 33
- Average age of the family = 34 years

To find: B - C

Step 1: Finding the values of A, B, C, and D
We are given that the average age of the family is 34 years. Therefore, the sum of their ages is 34 * 4 = 136 years.

We know that A - B = 3, so A = B + 3.

From the given information, we can also deduce that D = C * (33/C) = 33.

Now, substituting the values of A and D in the sum of their ages equation, we get:
A + B + C + D = (B + 3) + B + C + 33 = 136

Simplifying the equation, we have:
2B + 2C + 36 = 136
2B + 2C = 100
B + C = 50

Step 2: Finding B - C
We need to find the value of B - C.

Substituting the value of B + C from the previous step, we have:
B - C = (B + C) - 2C = 50 - 2C

To solve this equation, we need to find the value of C.

From the given information, we know that B * C = 78. We can find the factors of 78 to determine the possible values of B and C.

The factors of 78 are: 1, 2, 3, 6, 13, 26, 39, 78.

Since B + C = 50, the possible values of B and C are:
(1, 49), (2, 48), (3, 47), (6, 44), (13, 37), (26, 24)

Out of these possibilities, we need to find the value of C that satisfies the equation B * C = 78.

The only value that satisfies this equation is B = 13 and C = 37.

Substituting these values in B - C, we have:
B - C = 13 - 37 = -24

However, the age cannot be negative. Therefore, we need to find the absolute value of B - C, which is 24.

Thus, the correct answer is option D) 22.
Free Test
Community Answer
In a family, the age of father, mother, son, and grandson are A, B, C,...
Given:
A - B = 3, B + C = 78, C + D = 33 and the average age of the family is 34 years
Formula used:
Total age = Average age × total number of peoples
Calculation:​
Total age of the family = 4 × 34 = 136 years
A + B + C + D = 136
⇒ A + B = 136 – 33     (∵ C + D = 33)
A + B = 103 years      ---- (i)
A – B = 3 years (Given)      ----- (ii)
From (i) and (ii)
2A = 106 years
∴ A = 53 years
B = 103 – 53 = 50 years    ( from i )
Also C + B = 78    (Given)
⇒ C = 78 – 50 = 28 years
∴ B – C = 50 – 28 = 22 years
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In a family, the age of father, mother, son, and grandson are A, B, C, and D respectively. Given that A - B = 3, B + C = 78, C + D = 33 and the average age of the family is 34 years, then (B - C) is:a)19b)20c)21d)22Correct answer is option 'D'. Can you explain this answer? for SAT 2026 is part of SAT preparation. The Question and answers have been prepared according to the SAT exam syllabus. Information about In a family, the age of father, mother, son, and grandson are A, B, C, and D respectively. Given that A - B = 3, B + C = 78, C + D = 33 and the average age of the family is 34 years, then (B - C) is:a)19b)20c)21d)22Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for SAT 2026 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In a family, the age of father, mother, son, and grandson are A, B, C, and D respectively. Given that A - B = 3, B + C = 78, C + D = 33 and the average age of the family is 34 years, then (B - C) is:a)19b)20c)21d)22Correct answer is option 'D'. Can you explain this answer?.
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