Math Problem Statement

Can the company conclude, at the 0.05 level of significance, that the mean assembly time for Process 2 exceeds that of Process 1?

Solution

Let's analyze the provided image and break it into steps for solving the hypothesis testing problem.


(a) State the null and alternative hypotheses:

The hypotheses are:

  • H0:μd0H_0: \mu_d \leq 0 (The mean assembly time for Process 2 does not exceed Process 1.)
  • H1:μd>0H_1: \mu_d > 0 (The mean assembly time for Process 2 exceeds Process 1.)

(b) Determine the type of test statistic to use:

Since the population standard deviation is not provided and we are comparing means based on paired samples, we use a t-test for paired samples.


(c) Find the value of the test statistic:

To calculate the t-statistic:

  1. Compute the differences (di=Process 1Process 2d_i = \text{Process 1} - \text{Process 2}):

    d=[11,10,11,12,9,7,4,5,13,12]d = [-11, -10, -11, -12, -9, -7, -4, -5, -13, -12]

  2. Calculate the sample mean of the differences (dˉ\bar{d}):

    dˉ=din=11+(10)+(11)+(12)+(9)+(7)+(4)+(5)+(13)+(12)10\bar{d} = \frac{\sum d_i}{n} = \frac{-11 + (-10) + (-11) + (-12) + (-9) + (-7) + (-4) + (-5) + (-13) + (-12)}{10}

  3. Calculate the sample standard deviation of the differences (sds_d):

    sd=(didˉ)2n1s_d = \sqrt{\frac{\sum (d_i - \bar{d})^2}{n - 1}}

  4. Compute the t-statistic:

    t=dˉsd/nt = \frac{\bar{d}}{s_d / \sqrt{n}}


(d) Find the critical value at the 0.05 level of significance:

  • Degrees of freedom (df=n1=101=9df = n - 1 = 10 - 1 = 9).
  • Use the t-distribution table or calculator for a one-tailed test at α=0.05\alpha = 0.05.

(e) Decision:

  • Compare the calculated t-statistic with the critical t-value.
  • If t>tcriticalt > t_{\text{critical}}, reject H0H_0; otherwise, fail to reject H0H_0.

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
t-test for Paired Samples

Formulas

t = (x̄_d) / (s_d / sqrt(n))
s_d = sqrt(Σ(d_i - x̄_d)^2 / (n - 1))
Degrees of freedom (df = n - 1)

Theorems

t-distribution critical value

Suitable Grade Level

Undergraduate Statistics