Question

A piggy bank contains hundred 50-p coins, seventy 1 coin, fifty Rs. 2 coins and thirty 5 coins. If it is equally likely that one of the coins will fall out when the bank is turned upside down, what is the probability that the coin

(i) will be a 1 coin

(ii) Will not be a 5 coin

(iii) Will be 50 - p or a 2 coin?

Answer 1

Number of 50 paise coins = 100
Number of 1 rupee coins = 70
Number of 2 rupee coins = 50
Number of 5 rupee coins = 30
So, total number of coins = 100+70+50+30 = 250

or total outcomes = 250

(i) will be a 1 coin

favourable outcomes = number of 1 rupee coins = 70

Probability(getting 1 coin) = $\frac{70}{250}=\frac{7}{25}$

(ii) Will not be a 5 coin

favourable outcomes = total outcomes - chance of getting 5 coin = total outcomes - umber of 5 rupee coins = 250 - 30 = 220

Probability(not getting 5 coin) = $\frac{220}{250}=\frac{22}{25}$

(iii) Will be 50 - p or a 2 coin

favourable outcomes = chance of getting 50p coin +chance of getting 2 coin = number of 50 paise coins + number of 2 coins -= 100 + 50 = 150

Probability(getting 0 - p or a 2 coin) = $\frac{150}{250}=\frac{3}{5}$