Find the standard deviation of the average and the probability of 5 tubes will be less than 341 ml.?

A company sells sunscreen in 350 milliliter (ml) tubes. In fact, the amount of lotion in a tube varies according to a normal distribution with mean μ=347 ml and standard deviation σ=4 ml. Suppose a store which sells this sunscreen advertises a sale for 5 tubes for the price of 4. Consider the average amount of lotion from a SRS of 5 tubes of sunscreen and find:

(a) The standard deviation of the average, x¯ : ?

(b) The probability that the average amount of sunscreen from 5 tubes will be less than 341 ml.

Answer: ?

1 Answer

  • alex
    Lv 7
    2 years ago


    σ / sqrt(5)=1.79


    Pr(X<341)= calculator ...= 0.000398

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