T1.4 Suppose that 30% of all people who buy a new Iphone also buy an Apple watch. Consider randomly selecting 20 people who bought a new Iphone, and let X be the number of those who also bought an...

T1.4

Suppose that 30% of all people who buy a new Iphone also buy an Apple watch. Consider randomly selecting 20 people who bought a new Iphone, and let X be the number of those who also bought an Apple watch.

a) Find the probability that at least 6 of them bought an Apple watch.

b) Find the probability that between 4 and 10 of them, inclusive, bought an Apple watch.