Sign on the pumps at a gas station encourages customers to have their oil checked, and claims that one out of 6 cars needs to have oil added?
A. One out of the next four cars needs oil.
B. Two out of the next eight cars needs oil.
C. 10 out of the next 40 cars needs oil.
- PuzzlingLv 710 months ago
Use the binomial probability formula.
P(X = k) = C(n,k) * p^k * q^(n-k)
n : number of trials (4)
k : number of successes (1)
p : probability of success (1/6)
q : probability of failure (1 - p = 5/6)
P(X = 1) = C(4,1) * (1/6)^1 * (5/6)^3
= 4 * 125/1296
= 125/324 (or ~38.6%)
P.S. C(n,k) is the "n choose k" formula
C(n,k) = n! / (k! (n-k)!)
Now you should have all the information needed to solve B and C.