Question

Every product manufactured by a company goes through 6 different tests before being shipped out. It is known that the probability that a product passes any single test is 0.9 and the tests are independent. Only those products that pass the first three tests and also pass at least one of the three remaining tests are shipped out. Find the probability that a manufactured product is shipped out.

Answer 1

The Probability that the product is shipped out is 0.7283

Explanation:

Here, we are given that, a product passes through 6 tests before it is shipped out and a product is shipped out only if it passes all the first 3 tests and at least 1 of the remaining 3 tests.

We have P(pass)= 0.9, is the Probability of passing any test.

Which implies, P(fail)= 1- 0.9= 0.1

We have to find the Probability that the product is shipped out.

P(product is shipped out) = P(it passes first 3 tests )*P(passes at least 1 of the remaining 3 tests) •••••••••••(i)

We can take the product as the tests are Independent.

Now, let us obtain

P(it passes first 3 tests ) = P(pass)*P(pass)*P(pass)

=P(pass)]^3 = (0.9)^3 = 0.729

Hence, P( it passes first 3 tests)= 0.729 •••••••(ii)

Now,

P(passes at least 1 of the remaining 3 tests)

= 1-P(fails all the 3 remaining tests)

= 1-(0.1)^3 = 1 - 0.001 = 0.999

Hence,

P(passes atleast 1 of the remaining 3 tests)=0.999 ••••••••(iii)

Now, substituting the 2nd and 3rd equations in the first equation, we have;

P(product is shipped out) = P(it passes first 3 tests )*P(passes at least 1 of the remaining 3 tests)

= (0.729)*(0.999)

= 0.728271

= 0.7283