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1. Sixteen randomly sampled students were asked how many hours of video games th

ID: 3224332 • Letter: 1

Question

1. Sixteen randomly sampled students were asked how many hours of video games they played in the past week. x    = 3.6 hr and s = 3 hr. What is the test statistic for testing whether the mean for all BYU students is lower than 6 h/week?
A. (3.6 – 6) / 4
B. (3.6 – 3) / 6  
C. (3.6 – 6) / 0.75  
D. (3.6 – 6) / 1.333

2. Sixteen randomly sampled students were asked how many hours of video games they played in the past week. x    = 3.6 hr and s = 3 hr. For 95% confidence and 15 degrees of freedom, t* = 2.13. The stemplot was somewhat skewed to the right, with no outliers. What is the 95% confidence interval for ?   A. 3.6 ± (2.13 × 3)
B. 3.6 ± (2.13 × 3/4)
C. 3.6 ± (2.13 × 3/16)
D. 3.6 ± (2.13 × 3 × 16)

3. A dairy scientist compared milk production of cows fed two diets. He randomly divided a set of 21 cows into two groups. One group was fed diet 1 for a month, and the other was fed diet 2 for a month.
Here are the milk-production results (lb/week):
group   n        x.       s
diet 1 11   385.7   25.7
diet 2 10   398.2   43.1

4. What is the standard error of x1 x2?
A. 25.7÷11 + 43.1÷10
B. square root of 25.7÷11 + 43.1 ÷ 10
C. square root of 25.7^2 ÷11 - 43.1^2 ÷10
D. square root of 25.7^2 ÷11 + 43.1^2 ÷10

5. Using Option 2, the two-sample t statistic for this situation has an approximate t distribution with how many degrees of freedom?
A..     9
B..    10
C..   18
D..    20

Explanation / Answer

Answer:

1. Sixteen randomly sampled students were asked how many hours of video games they played in the past week. x    = 3.6 hr and s = 3 hr. What is the test statistic for testing whether the mean for all BYU students is lower than 6 h/week?
A. (3.6 – 6) / 4
B. (3.6 – 3) / 6  
Answer: C. (3.6 – 6) / 0.75  
D. (3.6 – 6) / 1.333

2. Sixteen randomly sampled students were asked how many hours of video games they played in the past week. x    = 3.6 hr and s = 3 hr. For 95% confidence and 15 degrees of freedom, t* = 2.13. The stemplot was somewhat skewed to the right, with no outliers. What is the 95% confidence interval for ?   A. 3.6 ± (2.13 × 3)
Answer: B. 3.6 ± (2.13 × 3/4)
C. 3.6 ± (2.13 × 3/16)
D. 3.6 ± (2.13 × 3 × 16)

3. A dairy scientist compared milk production of cows fed two diets. He randomly divided a set of 21 cows into two groups. One group was fed diet 1 for a month, and the other was fed diet 2 for a month.
Here are the milk-production results (lb/week):
group   n        x.       s
diet 1 11   385.7   25.7
diet 2 10   398.2   43.1

4. What is the standard error of x1 x2?
A. 25.7÷11 + 43.1÷10
B. square root of 25.7÷11 + 43.1 ÷ 10
C. square root of 25.7^2 ÷11 - 43.1^2 ÷10
Answer: D. square root of 25.7^2 ÷11 + 43.1^2 ÷10

5. Using Option 2, the two-sample t statistic for this situation has an approximate t distribution with how many degrees of freedom?
Answer: A..     9   ( smaller sample size-1)
B..    10
C..   18
D..    20