Question

A has a total of 21 coins, comprising ₹ 5, ₹ 2 and ₹ 1 coins. Find the minimum no. of ₹ 1 coins with A if he has at least one coin of each, and the value of coins is ₹ 42.

पर्याय

• 4

• 3

• 1

• 2

Answer 1

3

Explanation:

Let a. b, c be ₹ 1, 2 and 5 coins respectively, then a + b + c = 21

Also a + 2b + 5c = 42

a + 2b + 5c = 42
a +   b +   c = 21
        b + 4c = 21

When c = 1, b = 21 – 4 = 17 and a = 21 – (1 + 17) = 3

⇒ c = 2, b = 21 – 8 = 13 and a = 21 – (13 + 2) = 6

c = 3, b = 9, a = 9

So minimum no. of ₹ 1 coins = 3.