Answer to Question #247020 in Statistics and Probability for ADam

Question

There are 20 small batteries on sale in a minimarket. Due to careless handling, 4 of them become defective. A customer comes into the market and randomly selects 3 batteries at once. a) Find the probability that the customer selects exactly 1 defective battery.

Answer 1

Solution:

Total no. of batteries = 20

No. of defective batteries = 4

The probability that the customer selects exactly 1 defective battery

$=\dfrac{^3C_1 }{^{20}C_1} \\=\dfrac3{20}$