Suppose a geyser has a mean time between eruptions of 70 minutes. let the interval of time between the eruptions be normally distributed with standard deviation 18 minutes.
(a) what is the probability that a randomly selected time interval between eruptions is longer than 79 minutes?
(round to four decimal places as needed.)
(b) what is the probability that a random sample of 88 time intervals between eruptions has a mean longer than 79 minutes?
(round to four decimal places as needed.)
(c) what is the probability that a random sample of 27 time intervals between eruptions has a mean longer than 79 minutes?
(round to four decimal places as needed.)

Step-by-step explanation:

Let X be the geyser mean time between eruptions of 70 minutes.

X is N (70, 19)

a)

b) Sample size =88. Std error =

c) For sample size =27, std error =

P(X>79) = P(Z>2.46) =0.5-0.4931=0.0069

y = 2x

step-by-step explanation:

if you divide each number in the sequence, you'll see that they all have a multiple factor of 2. each number in the series, and any other numbers which may continue, will be multiplied by 2. therefore, y is the next number in the sequence, and x is the current one, so, our formula will be y = 2x.

answer: first option i.e. 'a' is correct.

step-by-step explanation:

since we have given that

number of minutes to wrap a small gift box = 4 minutes

we need to find the number of gifts to be wrapped in 5 minutes

since there is a direct variation, as the number of minutes will increase with   number of gifts to be wrapped.

so, let the number of gifts to be wrapped in 5 minutes be x.

so, it becomes,

hence, first option 'a'   is correct.