6. You are constructing a 90% confidence interval for a sample consisting of n = 9 values and an

unknown population standard deviation. The population appears to be very skewed. Determine

whether a margin of error should be calculated using a critical value of za/2, a critical value of ta/2, or neither.

a) a critical value of za/2

b) a critical value of ta/2

c) neither

7. The standard deviation of sample size of n = 15 is 345 and the mean is 6784. Given that the population follows a normal distribution, construct a 90% confidence interval estimate of the mean of the population.

a) 6519

b) 6593

c) 6627

d)6783

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation:

answer:   x = 3 + √11     and     x = 3 - √11

step-by-step explanation:

x² - 6x + 9 = 11

(x - 3)² = 11

x - 3 = ±√11

    x = 3 ± √11

x = 3 + √11     and     x = 3 - √11

step-by-step explanation:

; fx