Question

Mary works in a factory that produces t1000 telephones each day. when 30 phones were sampled, it was found that 9 were defective. estimate how many telephones are defective each day.

Answer 1

3/10 of phones are found defective each day. If 1,000 telephones are produced each day, about 300 of them will be defective.

Answer 2

The estimated number of defective phones produced each day is 0.3×t1000

Explanation:

The proportion of phones that were found defective is given by the following equation

Proportion of defective phone = (Number of defective phone)÷(Number of sampled phone)

∴ Proportion of defective phone = 9÷30 = 3÷10 = 0.3 or 30%

Therefore, based on the proportion, if t1000 telephones are produced, the estimated number of defective phones produced each day will be as follows

Proportion of defective phone × Number of produced phone

= 0.3 × t1000

The estimated number of defective phones produced each day = 0.3×t1000.