Answer:
205.81 to 214.19
Step-by-step explanation:
Sample size (n) = 50
Sample mean weight (X) = 210 grams
Sample standard deviation (s) = 18 grams
Confidence coefficient (Z) at 90% = 1.645
The confidence interval for the true mean breaking strength of cotton threads of this type, at a 90% confidence level, is given by:
The confidence interval is 205.81 grams to 214.19 grams.
Answer:
Step-by-step explanation:
Whenever we are doing unit conversions, we have to remember to make the first ratio and then each successive ratio should be put <em>in such a way</em> that the top and bottom cancels out with each unit and whatever we want, remains.
A simple example would be if we were to just convert from cm to mm. Suppose we want to convert 5 centimeters to millimeters. We can write the ratios is 2 ways:
First:
Second:
The first one is correct since we want mm, mm should be on top and cm should be on bottom form cm and cm to get canceled.
Now, for our problem, we want mm on top and day on bottom. So, cm and year should cancel. Looking at the first choice, the conversion factors are correct & skimming through, we see that
cm and cm cancels (top and bottom), also year and year cancels (top and bottom), it will leave us with mm on top and days on bottom, <em>which is what we want</em>.
First answer choice is right.
