Correct Answer - Option 3 : 7/10
Given:
A wallet has three denominations of coins – Rs. 1, Rs. 5 and Rs. 10 in the ratio of 2 ∶ 3 ∶ 5.
A coin is drawn at random.
Total number of coins = 30
Concepts used:
Number of coins of particular denomination = (Ratio of coins of given denomination/Sum of ratios) × Total number of coins
Probability that coin drawn is not a Rs. 5 coin = 1 – {P (Coin drawn is Rs. 5 coin)}
Calculation:
A wallet has three denominations of coins – Rs. 1, Rs. 5 and Rs. 10 in the ratio of 2 ∶ 3 ∶ 5 and there are total of 30 coins.
⇒ Number of Rs. 1 coins = 2/(2 + 3 + 5) × 30 = 6
⇒ Number of Rs. 5 coins = 3/(2 + 3 + 5) × 30 = 9
⇒ Number of Rs. 1 coins = 5/(2 + 3 + 5) × 30 = 15
Probability that coin drawn is not a Rs. 5 coin = 1 – (9/30) = 7/10
∴ Probability that coin drawn is not a Rs. 5 coin is 7/10.
