Two independent samples of sizes 20 and 25 are randomly selected from two normal populations with equal variances. In order to test the difference between the population means, the test statistic is: a. approximately standard normal random variable b. a standard normal random variable c. t-distributed with 43 degrees of freedom d. t-distributed with 45 degrees of freedom

Describe the relationship between the angles of similar triangles and the sides of similar triangles

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

Solve this problem! extra ! 3025/5.5 = a/90.75