Answer:
The required sample size increases.
Step-by-step explanation:
The margin of error of a confidence interval is given by:
In which z is related to the confidence level(the higher the confidence level the higher z), 
is the standard deviation of the population and n is the size of the sample.
In this question:
The confidence level decreases, so z decreases.
For the margin of error to stay the same, the sample size also has to decrease.
The required sample size increases.
The z score for a confidence level of 99% is 2.575.. You need to know this to complete this type of problem.. the other two commonly used confidence levels are 90% and 95% having z scores of 1.645 and 1.96 respectively. You need to memorize this!
To find the confidence interval, it will be defined as the sample mean plus/minus the margin of error.. Now to find the margin of error, divide the standard deviation of 12 by the square root of the number of elements in your sample(√250). Then take that result and multiply it by the Z score I mentioned above for a 99% confidence level.
In this case: the sample mean is 70 and the margin of error is approximately 1.95
So to calculate the confidence interval, do the following:
70 - 1.95 = 68.05 rounded to the nearest whole number is 68
70 + 1.95 = 71.95 rounded to the nearest whole number is 72
Looks like that would be the last choice. hope this helps.. it's been awhile since my work with statistics :-)
Radical Equation:
1. Isolate the radical expression.
2. Square both sides of the equation: If x = y then x2 = y2.
3. Once the radical is removed, solve for the unknown.
4. Check all answers.
Another way of saying it:
1. Isolate the radical expression involving the variable. ...
2. Raise both sides of the equation to the index of the radical.
3. If there is still a radical equation, repeat steps 1 and 2; otherwise, solve the resulting equation and check the answer in the original equation.
For 10 feet and 6 inches,
12 inches = 1 foot, therefore 6 inches = 6/12 foot = 0.5 foot
10 feet 6 inches = 10 + 0.5 = 10.5 feet
7 feet required 3 pints
1 foot would have required (3/7) pints
10.5 feet will then require: (3/7)*10.5 = 4.5 pints.
Therefore 10 feet and 6 inches will require 4.5 pints.
Percent means per 100
think cent as in 100 pennies in a dollar
To convert from percent to decimal, we divide by 100 or move the decimal over 2 spots, so,
15% = 15/100 = 0.15
Now multiply 0.15 by 850 to find the discount saved
0.15*850 = 127.50
So you'll save $127.50
The final price is therefore: 850-127.50 = 722.50
A shortcut is to multiply 850 by 0.85
850*0.85 = 722.50
We get the same answer
The 0.85 comes from the fact that if you get 15% off, then you pay 85% of the original price
Answer: $722.50
