![sahaitong1844](/avatars/15411.jpg)
sahaitong1844
17.06.2021 •
Mathematics
A random sample of 21 desktop PCs is selected. The mean life span is 6.8 years with a standard deviation of 2.4 years. Construct a 95% confidence interval for the mean life span of all desktop PCs. Assume that the life spans of all desktop PCs are approximately normally distributed (a) (5.85, 7.75) (b) (1.68, 3.12) (c) (5.60, 8.00) (d) (5.71, 7.89) (e) (5.77, 7.83)
Solved
Show answers
More tips
- S Science and Technology How to choose a home theater system?...
- H Health and Medicine Discover the Hidden Principles and Real Results of the Japanese Diet...
- C Computers and Internet Google Search Tips and Tricks: Everything You Need to Know...
- F Food and Cooking Experts Name Top 5 Healthiest Teas...
- F Food and Cooking From Latte to Espresso: Which Coffee Drink is the Most Popular on Earth?...
- F Food and Cooking How many stages of coffee roasting are there?...
- C Computers and Internet Porn Banner: What It Is and How to Get Rid Of It?...
- G Goods and services How to Choose a Coffee Maker? The Ultimate Guide for Coffee Lovers...
- C Computers and Internet How to Teach Older Generations to Work with Computers?...
- P Philosophy Unidentified Flying Object - What is the Nature of this Phenomenon?...
Answers on questions: Mathematics
- M Mathematics Find m 5 if m 1 = 100°. O a. 100° Ob. 180° O c. 90° d. 80° °...
- B Business Which of the following characteristics leads to an upward-sloping supply curve? 1.increasing opportunity costs 2.increasing marginal costs 3.diminishing marginal utility...
- G Geography Which plate forms a boundary with the African Plate? Pacific South American Australian Philippine...
- H History What metaphor is used in philippines that descibe the immortality of the soul?...
- C Chemistry Though alchemy was not a part of seven liberal arts curriculum in per-modern europe education, alchemical experiments caused important developments in metallurgy, porcelain...
- E English Tom offered to lend me some money to buy a present for my mother, was very kind of him....
Ответ:
(d) (5.71, 7.89)
Step-by-step explanation:
We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 21 - 1 = 20
95% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 20 degrees of freedom(y-axis) and a confidence level of
. So we have T = 2.086
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 6.8 - 1.09 = 5.71 years
The upper end of the interval is the sample mean added to M. So it is 6.8 + 1.09 = 7.89 years
So the confidence interval is (5.71, 7.89), and the correct answer is given by option b.
Ответ:
b,d,e
Explanation:
I took the assignment.