TEST XIII: MENTAL ABILITY SOLUTIONS

1. The sum of the present ages of a father and his son is 60 years. Six years ago, father’s age was five times the age of the son. After 6 years, what is the son’s age? a. 12 years b. 14 years c. 18 years d. 20 years
Explanation: Let the present ages of son and father be x and (60 -x) years respectively. Then, (60 - x) - 6 = 5(x - 6) 54 - x = 5x - 30 6x = 84 x = 14. Son's age after 6 years = (x+ 6) = 20 years.

2. 3 years ago the average age of a family of 5 members was 17 years. After A baby born, the Average age of the family is the same today. The present age of the baby is a. 1 year b. 1 ½ years c. 2 years d. 3 years

Explanation: Given that , 3 years ago, the average age of 5 members = 17 years. Total present age of 5 members = 17 × 5 + 3 × 5 = 100. Born on new baby , the average age of 6 members = 17 years. Total present age of 6 members = 17 × 6=102 ∴ Present age of child = 102 – 100 = 2 years

3. A television set was sold for ` 1,170 after giving successive discounts of 35% and 10% respectively. What was the marked price? a. 1800 b. 1700 c. 2000 d. 1900

Explanation: Let Marked Price be Z Rs.  Z x 65/100 x 90/100 =1170. Z = 2000

4. A man sold two gas stoves for `8400 each. He sold one at a gain of 20% and the other at a loss of 20%. Find his gain or loss %in the whole transaction.

• a. Neither Profit nor Loss
• b. Loss of 4%
• c. Profit of 4%
• d. Loss of 16%
Explanation: 20-20- (20 x 20/100) = -4%

5. A horse and two cows together cost Rs. 680. If a horse cost Rs. 80 more than a cow then the ratio of cost of horse and cow is A. 7:5 B. 5:7 C. 8:9 D. 9:8

Explanation:
Let the cost of a horse be Rs. x.
Let the cost of cow be Rs. y
x + 2y = Rs.680.... (1)
x - y =Rs.80 ... (2)
.................................
3y = Rs. 600 So y = Rs.200 x - 200 = 80 x = 280 x : y = 280 : 200 = 7 : 5