Question

Estimates of a forest’s biomass, the total amount of vegetation held by the forest, are important in determining the amount of unabsorbed carbon dioxide that we can expect to remain in the atmosphere. A random sample of 55 plots selected from North America’s boreal forest produced a mean biomass of ¯ x = 4.2 kg/m2 with a standard deviation of s = 1.5 kg/m2. Find a 92% confidence interval for the mean biomass for the boreal forests. Round your final answer to two decimal places.

Answer 1

Solution :

Given that,

= 4.2

s =1.5

n = 55

Degrees of freedom = df = n - 1 =55 - 1 = 54

At 92% confidence level the t is ,

t/2,,df = t0.04,54 =1.784 ( using student t table)

Margin of error = E = t/2,,df * (s /n)

= 1.784 * (1.5 / 55)

= 0.36

The 92% confidence interval estimate of the population mean is,

- E < < + E

4.2 - 0.36< <4.2 + 0.36

3.84 < <4.56

( 3.84 ,4.56)