Answer:
96
Step-by-step explanation:
<u>Step 1
</u>
Divide your confidence interval by 2. In this case the confidence is 95% = 0.095, so 0.095/2 = 0.0475
<u>Step 2
</u>
Use either a z-score table or a computer to find the closest z-score for 0.0475 and you will find this value is 1.96
<u>Step 3
</u>
Divide the margin error by 2. In this case, the margin error is 2%. When dividing this figure by 2, we get 1% = 0.01
<u>Step 4
</u>
Divide the number obtained in Step 2 by the number obtained in Step 3 and square it
1.96/0.01 = 196 and 196 squared is 38,416
<u>Step 5
</u>
As we do not now a proportion of people that purchase on line, we must assume this value is 50% = 0.5. Square this number and you get 0.25
<u>Step 6
</u>
Multiply the number obtained in Step 5 by the number obtained in Step 4, round it to the nearest integer and this is an appropriate size of the sample.
38,416*0.25 = 9,604
Answer:
75 minutes
Step-by-step explanation:
The rate at which the tank is filled up, F, and emptied, E, are respectively:
Since V is the full volume of the tank, the time required to fill the tank if both pipes are open is given by:
It will take 75 minutes to fill the tank if both pipes are open.
A² - ab + 8b + b² - 1
There are 5 terms in the expression.
a² = 1st term
ab = 2nd term
8b = 3rd term
b² = 4th term
1 = 5th term
Each term is separated by a plus (+) sign or a minus (-) sign.
A term is either a number, a variable, or a number and a variable multiplied together.
a², ab, b² are variables.
8b is a number and a variable multiplied together
1 is a number.
Try using the back of the book.
