Question

Joan’s Nursery specializes in custom-designed landscaping for residential areas. The estimated labour cost associated with a particular landscaping proposal is based on the number of planting of trees, shrubs, and so on to be used for the project. For cost-estimating purposes, managers use two hours of labour time for the planting of a medium-sized tree. Actual times from a sample of 10 planting during the past month follow (times in hours).

1.7 1.5 2.6 2.2 2.4 2.3 2.6 3.0 1.4 2.3
Test to see whether the mean tree-planting time differs from two hours.
State the null and alternative hypothesis

Answer 1

H0 : μ = 2

H1 : μ > 2

We fail to reject the null and conclude that no significant evidence exists to support that mean tree-planting time differs from two hours.

Explanation:

Given :

X = 23.71,17.79,29.87,18.78,28.76

Sample mean, xbar = Σx / n = 22/10 = 2.2

Standard deviation, s = 0.516 (calculator)

H0 : μ = 2

H1 : μ > 2

Test statistic :

(xbar - μ) ÷ (s/sqrt(n))

n = 10

Test statistic :

(2.2 - 2) ÷ (0.516/sqrt(10))

0.2 / 0.1631735

Test statistic = 1.23

Using the Pvalue from Tscore calculator, df = n - 1 = 10 - 1 = 9

Pvalue(1.23, 9) = 0.1249

Since, Pvalue > α ; We fail to reject the null and conclude that no significant evidence exists to support that mean tree-planting time differs from two hours.