The average particle density in the milky way galaxy is about one particle per cubic centimeter. express this number in si units kg/m^3. assume that the universe is made up of 70% hydrogen and 30% helium. be very detailed with how you come up with the numbers..

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’s #16 asking me and how do i solve it?

The earth exerts a gravitational force of 500 n on amy. what is amy’s mass in kg?