Abox contains 8 green and 4 blue marbles. two marbles are selected (at once with no replacement). find the expected number of green marbles among the selected ones.

20 da is equal to a. 2,000 cm. b. 2 m. c. 20,000 cm. d. 20,000 mm

Rectangle leg this 11feet and perimeter of 38feet what is the width of the rectangle in feet

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.