Answer:
a) 0.25249
b) 0.66575
Step-by-step explanation:
We solve this question using z score formula
= z = (x-μ)/σ, where
x is the raw score
μ is the population mean = 23.2 gallons
σ is the population standard deviation = 2.7 gallons
a) Find the probability that a randomly selected American drinks more than 25 gallons of bottled water in a year.
For x = 25 gallons
z = 25 - 23.2/2.7
z = 0.66667
Probability value from Z-Table:
P(x<25) = 0.74751
P(x>25) = 1 - P(x<25)
1 - 0.74751
= 0.25249
The probability that a randomly selected American drinks more than 25 gallons of bottled water in a year is 0.25249
2) What is the probability that the selected person drinks between 22 and 30 gallons
For x = 22 gallons
z = 22 - 23.2/2.7
z = -0.44444
Probability value from Z-Table:
P(x = 22) = 0.32836
For x = 30 gallons
z = 30 - 23.2/2.7
z =2.51852
Probability value from Z-Table:
P(x = 30) = 0.99411
The probability that the selected person drinks between 22 and 30 gallons is
P(x = 30) - P(x = 22)
= 0.99411 - 0.32836
= 0.66575
