Please help me with this one!

Three coins are flipped. what is the probability that there will be at least two tails?

How many of the 250 grandparents in the population would you expect to prefer online shopping with merchant a? merchant a: 4 merchant b: 6 merchant c: 2 merchant d: 3 other: 5 none: 5 answer choices: a.about 4 b.about 8 c.about 40 d.about 21

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base