Kent can paint a certain room in 6 hours, but kendra needs 4 hours to paint the same room. how long does it take them to paint the room if they work together?

Suppose there are 10 five and six-year-old attending a birthday party. when a 30 year old mother walks into the room with an infant in her arms, what happens to the mean age in the room? what happens to the standard deviation of ages in the room? a. the mean and standard deviation of both change. b. the meaning will change, but the standard deviation will stay approximately the same. c. i mean will stay approximately the same, but the standard deviation will change. d. the mean and standard deviation will both stay approximately the same.

Ineed to know the answer right now! !

If the value of cos330°is√3/2 then find cos 165°.