Atrain 471 m long is moving on a straight track with a speed of 75.1 km/h. the engineer applies the brakes at a crossing, and later the last car passes the crossing with a speed of 15 km/h. assuming constant acceleration, determine how long the train blocked the crossing. disregard the width of the crossing. answer in units of s.

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.

Which is the best for showing percentages of different types of cars sold(gas hybrid , electric , other ) in the united states ?

An incident ray through the focal point of a spherical mirror will: reflect through the center of curvature. reflect back through the focal point. reflect parallel to the principle axis. reflect the same direction as the incident ray.