Question

Last year, the revenue for medical equipment companies had a mean of 80 million dollars with a standard deviation of 23 million. Find the percentage of companies with revenue less than 18 million or more than 142 million dollars. Assume that the distribution is normal. Round your answer to the nearest hundredth.

Answer 1

Solution:-

Given that,

mean = = 80

standard deviation = = 23

P(x < 18 or x > 142 )

= P[(x - ) / < (18 - 80) / 23] + 1- p P[(x - ) / < (142 - 80) / 23]

= P(z < -2.70) + 1- P(z < 2.70)

= 0.0035 + ( 1 - 0.9965 )

= 0.0035 + 0.0035

= 0.0070

percentage = 0.70%