Question

8. value: 10.00 points An experiment was conducted to determine the effectiveness of a method designed to remove oil wastes found in soil. Three contaminated soil samples were treated. After 95 days, the percentage of contamination removed from each soil sample was measured, with a mean of 49.3 percent and a standard deviation of 1.5 percent. If we wished to narrow the boundary around u for a 98 percent confidence interval to within 0.5 percent, how many soil samples should be in our experiment. O 437 Oo oo

Answer 1

8)

Answer)

As the population s.d is unknown we will use t distribution

N = 3

Df = n-1 = 2

From t table for 2 df and 98% confidence level critical value t is = 6.965

Margin of error = t*s.d/√n

We need to find n

0.5 = 6.965*1.5/√n

N = 437

4)

We need to use standard normal z table to estimate the answer here

Critical value z from z table for 95% confidence level is 1.96

Margin of error (MOE) = z*√p*(1-p)/√n

P = 0.5

Moe = 0.01

After substitution

N = 9604