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tekilochka [14]
3 years ago
12

A company makes batteries with an average life span of 300 hours with a standard deviation of 75 hours. Assuming the distributio

n is approximated by a normal curve fine the probability that the battery will last:(give 4 decimal places for each answer)
a. Less than 250 hours

b. Between 225 and 375 hours

c. More than 400 hours
Mathematics
1 answer:
Keith_Richards [23]3 years ago
4 0
Idk tbh, maybe the answer is A.
You might be interested in
In the right triangle shown, A= 30° and AB = 8.
zloy xaker [14]

Answer:

BC=4\ units

Step-by-step explanation:

The picture of the question in the attached figure

we know that

sin(30^o)=\frac{BC}{AB} ----> by SOH (opposite side divided by the hypotenuse)

we have

AB=8\ units\\\\sin(30^o)=\frac{1}{2}

solve for BC

BC=sin(30^o)(AB)

substitute the values

BC=(\frac{1}{2})(8)

BC=4\ units

4 0
2 years ago
Mark can remember only the first 4 digits of his friend's phone number. He also knows that the number has 7 digits and that the
denis-greek [22]

Answer:

<em>19800 seconds, or 330 minutes, or 5 hours + 30 minutes</em>

Step-by-step explanation:

<u>Number Permutations</u>

We know the phone number has 7 digits, 4 of which are known by Mark. This leaves him 3 digits to guess with. We also know the last one is not zero. The number can be represented as

XXY

Where X can be any digit from 0 to 9 and Y can be any digit from 1 to 9. The first two can be combined in 10x10 ways, and the last one can be of 9 ways, this gives us 10x10x9 = 900 possible permutations.

If each possible number takes him 22 seconds, every possibility will need

22x900=19800 seconds, or 330 minutes, or 5 hours + 30 minutes

3 0
2 years ago
Nancy bought 5 1/2 pounds of apples and oranges. If she bought 1 2/3 pounds of apples, which of the following equations could be
poizon [28]

Answer:

5 1/2-p=1 2/3

Step-by-step explanation:

let p represent the weight of the oranges!

6 0
3 years ago
Can you so me work for7\10-1\2
Rina8888 [55]
Well, 1/2 is equal to 5/10... so 7/10 - 5/10 is 2/10 because 7-5=2 :)
5 0
3 years ago
Read 2 more answers
What is the formula for a confidence interval?
ikadub [295]

Answer:

a) The formula is given by mean \pm the margin of error. Where the margin of error is the product between the critical value from the normal standard distribution at the confidence level selected and the standard deviation for the sample mean.

b) \bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".  

The margin of error is the range of values below and above the sample statistic in a confidence interval.  

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".  

If the distribution for X is normal or if the sample size is large enough we know that the distribution for the sample mean \bar X is given by:

\bar X \sim N(\mu, \frac{\sigma}{\sqrt{n}})

Part a

The formula is given by mean \pm the margin of error. Where the margin of error is the product between the critical value from the normal standard distribution at the confidence level selected and the standard deviation for the sample mean.

Part b

The confidence interval for the mean is given by the following formula:  

\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}

5 0
3 years ago
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