Question

Ava teaches a ceramics class on the weekends. In Sunday's class, the students created 7 clay objects, 5 of which were plates. After each class, Ava bakes the clay objects in a hot kiln to harden them. Students pick up their finished pieces later in the week. If Ava randomly chose 4 clay objects to bake in the kiln Sunday night, what is the probability that all of them are plates ? Write your answer as a decimal rounded to four decimal places.

Answer 1

Given data:

7 clay objects out of which 5 are plates

If Ava randomly chose 4 clay objects to bake in the kiln Sunday night.

These are the possibilities:

At the first selection: 5 plates out of 7 clay objects will be selected

At the second selection: The number of plates will be reduced to 4 plates and the number of clay objects will now be 6

Similarly, at the third selection, 3 plates will be selected from 5 clay objects

At the fourth selection, 2 plates will be selected from 4 clay objects.

Therefore the probability that all 4 of them are plates will be:

`(5)/(7)*(4)/(6)*(3)/(5)*(2)/(4)`

=>

`(120)/(840)=(1)/(7)`

=>

`(1)/(7)=0.1429`

Answer = 0.1429