Mathematics Problem Solving Flashcards

A man is 4 times as old as his son. In 10 years, the man will be 3 times as old as his son. How old is the son now?

Answer: 20

Let son's age = x. Man's age = 4x. In 10 years: 4x + 10 = 3(x + 10). 4x + 10 = 3x + 30. x = 20.

A container has a capacity of 2.5 litres. How many such containers are needed to hold 18 litres of juice?

Answer: 8

18 ÷ 2.5 = 7.2. Since you cannot use a fraction of a container, you need 8 containers.

The average of four numbers is 25. Three of the numbers are 18, 27, and 30. What is the fourth number?

Answer: 25

Total of 4 numbers = 25 × 4 = 100. Sum of three numbers = 18 + 27 + 30 = 75. Fourth number = 100 − 75 = 25.

A triangle has a base of 12 cm and a height of 9 cm. What is its area?

Answer: 54 cm²

Area of triangle = 1/2 × base × height = 1/2 × 12 × 9 = 54 cm².

Priya and Raj have $180 altogether. If Priya gives Raj $20, they will have the same amount. How much does Priya have originally?

Answer: $110

After giving $20: both have $180 ÷ 2 = $90. So Priya originally had $90 + $20 = $110.

A fruit seller had 2,400 oranges. He sold 3/8 of them on Day 1 and 5/12 of the remainder on Day 2. How many oranges were left?

Answer: 875

Day 1 sold: 3/8 × 2,400 = 900. Remainder = 1,500. Day 2 sold: 5/12 × 1,500 = 625. Left: 1,500 − 625 = 875.