Answer:
A) 68.33%
B) (234, 298)
Step-by-step explanation:
We have that the mean is 266 days (m) and the standard deviation is 16 days (sd), so we are asked:
A. P (250 x < 282)
P ((x1 - m) / sd < x < (x2 - m) / sd)
P ((250 - 266) / 16 < x < (282 - 266) / 16)
P (- 1 < z < 1)
P (z < 1) - P (-1 < z)
If we look in the normal distribution table we have to:
P (-1 < z) = 0.1587
P (z < 1) = 0.8413
replacing
0.8413 - 0.1587 = 0.6833
The percentage of pregnancies last between 250 and 282 days is 68.33%
B. We apply the experimental formula of 68-95-99.7
For middle 95% it is:
(m - 2 * sd, m + 2 * sd)
Thus,
m - 2 * sd <x <m + 2 * sd
we replace
266 - 2 * 16 <x <266 + 2 * 16
234 <x <298
That is, the interval would be (234, 298)
Answer:
3
Step-by-step explanation:
Answer:
$99/$115 x 100% = 86.086% of the original price
So 100% - 86.086
= 13.9 = 14%
Or you could just do (115 - 99) x 100 which gets the same answer.
Problem 1
The error is 2 inches since her estimate is 2 inches off the true value.
We can think of it like this
4 feet = 4*12 = 48 inches
4 feet, 2 inches = 4 ft + 2 in = 48 in + 2 in = 50 inches
So she guesses he is 48 inches, but he's really 50 inches, so 50-48 = 2 inches is her error.
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Problem 2
Divide the error (2 inches) over the actual height (50 inches) to get
2/50 = 4/100 = 4%
The percentage error is 4%
This means she is 4% off the target.
Note how 4% of 50 = 0.04*50 = 2 which was the error we found back in problem 1.
