A​ four-year study of various brands of bottled water found that 25​% of bottled water is just tap water packaged in a bottle. Consider a sample of sevenseven ​bottled-water brands, and let x equal the number of these brands that use tap water. Complete parts a through d.

a. Is x​ (approximately) a binomial random​ variable?
b. Give the probability distribution for x as a formula.
c. Find p(x = 2).
d. Find P(x <= 1).