Certain tubes manufactured by a company have a mean lifetime of 800 hours and a standard deviation of 6 hours. Find the probability that a random sample of 16 tubes taken from the group will have a mean lifetime (a) between 790 and 810 hours, (b) less than 785 hours, (c) more than 820 hours.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

graph b

step-by-step explanation:

one solution- graph a (clear intercepting point.)

no solution- graph b (they're parallel, there will never be a point of interception.)

infinite solutions- graph c (all points intercept.)

6.25 grams

step-by-step explanation: