121 is big enough to assume normality and not worry about the t distribution. By the 68-95-99.7 rule a 95% confidence interval includes plus or minus two standard deviations. So 95% of the cars will be in the mph range
The question is a bit vague, but it seems we're being asked for the 95% confidence interval on the average of 121 cars. The 121 is a hint of course.
The standard deviation of the average is in general the standard deviation of the individual samples divided by the square root of n:
So repeating our experiment of taking the average 121 cars over and over, we expect 95% of the averages to be in the mph range
That's probably the answer they're looking for.
Answer:
1 over x 2
Step-by-step explanation:
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Answer: The answer is 252
Step-by-step explanation:
:)))
You want to compare the square root of 55 using "mental math". Start off by choosing two perfect squares that you can think of that are close to 55.
If you don't know perfect squares then start with the number 2 and multiply it by itself. 2 times 2 equals 4, so 4 is a perfect square.
Take the number 3, multiply it by itself, and so on. Do this for all the numbers until you find two perfect squares that are close to 55.
The two perfect squares closest to 55 are the square roots of 49 and 64. Find the square root of these numbers.
√49 = 7
√64 = 8
Calculate how far 55 is from 49 and 64. 55 is 6 digits away from 49 and 9 digits away from 64.
This means the square root of 55 will be closer to the square root of 49; 7. Since we know that it will be closer to 7, you can put the less than sign for your answer.
√55 < 7.7
(The actual square root of 55 is ~7.4, so we were correct in determining the answer without using a calculator!)
