The arithmetic mean of eight positive integers is 7. If one of the eight integers is removed, the mean becomes 6. What is the value of the integer that is removed?

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?

Aplane intersects a pris paralel to the base of the prism. the cross section is a polygon wth eight sides. how many sides does the base of the prism have? a. 10 b. 8 c. 7 d. 9