Classify the hypothesis test as two-tailed, left-tailed, or right-tailed. At one school, the average amount of time that tenth-graders spend watching television each week is hours. The principal introduces a campaign to encourage the students to watch less television. One year later, the principal wants to perform a hypothesis test to determine whether the average amount of time spent watching television per week has decreased from the previous mean of 21.6 hours.

a. Two-tailed
b. Right-tailed
c. Left-tailed

C: left tailed

Step-by-step explanation:

In two tailed hypothesis, the alternative hypothesis is when mean can either be lesser or greater than the given value. Usually uses the symbol ≠.

In right tailed, the alternative hypothesis is when the mean is greater than the given value.

In left tailed, the alternative hypothesis is when the mean is lesser than the given value.

In this question, the hypothesis test to be performed is to determine if the average amount of time spent watching television per week has decreased from the given value of 21.6 hours.

Thus, it is left tailed test.

(n^3 - n)

= n(n-1)(n+1)

since it is divisible by 3 and 2 ,because it is a multiple 3 consecutive number

if, n-1 is odd then n+1 is also odd, then it is a multiple of 9

but if, n-1 is even then n+1 is also even, then it is a multiple of 4

so, largest multiple = max(9*2, 4*3) = max(18, 12) = 18

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take good notes.

do your homework.

use mnemonics and other tricks.

do practice tests.

note: the best i know.