Can I pls get help with this question

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.

Yosef can eat 21 jamuns while rose can eat just 15 . complete the blank. yosef can eat % more jamuns than rose.

What is the result of adding the system of equations? 2x+y=4 3x-y=6