Answer:
a. The expected number of adults who smoke is 70
b. The probability that fewer than 20 smoke is 5.7%
c. The probability that from 45 to 80 smoke is the 12,8% to 22,8%
d. The probability that 70 or more smoke is the 20%
Explanation:
a. 350 is the 100% so you have to do a equation
350 -100%
 X  - 20% =  20% x 350/100  = 70 adults
b. 350 -100%
  20  - X = 20% x 100%/350= 5.7% probability
c. 350 - 100%
  45  -  X = 45 x 100%/350= 12.8% probability
  350 - 100%
  80  -  X = 80 x 100%/350= 22.8% probability
d. 350 - Â 100%
  70  -  X = 70 x 100%/350= 20%  probability