Explain why a school bus is a compound machine

An insurance company wants to know if the average speed at which men drive cars is higher than that of women drivers. the company took a random sample of 27 cars driven by men on a highway and found the mean speed to be 72 miles per hour with a standard deviation of 2.2 miles per hour. another sample of 18 cars driven by women on the same highway gave a mean speed of 68 miles per hour with a standard deviation of 2.5 miles per hour. assume that the speeds at which all men and all women drive cars on this highway are both approximately normally distributed with unknown and unequal population standard deviations.

What is the role of lenses in microscopy?

Astudent weighing 700 n climbs at constant speed to the top of an 8 m vertical rope in 10 s. the average power expended by the student to overcome gravity is most nearly