Question

A small grocery store had 12 cartons of milk, 2 of which were sour.

1. If David is going to buy the 8th carton of milk sold that day at random, compute the probability that he selects a carton of sour milk.

Enter a fraction (e.g. 2/10, no need to reduce it to the lowest form):

Answer 1

We have number of cartons of milk in a store is 12.

In that 2 cartons are sour milk.

We want the probability that 8th carton of milk is sour.

That is upto the 7 times, he gets non sour milk and in the 8th time, he gets sour milk.

There are 12-2=10 non sour carton of milk.

There are two options:

1. One sour carton is there at the time of 8th selection

2. Two sour cartons are there at the time of 8th selection

Therefore, the required probability is: