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zimovet [89]
3 years ago
12

What is the complement of 57?

Mathematics
1 answer:
umka21 [38]3 years ago
4 0
Complements are numbers that add 90. Since one is 57, the other has to add to 57. So 33 would add with 57 to get 90.
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A teacher gives a test to a large group of students. The results are closely approximated by a normal curve. Teh mean is 73, wit
zavuch27 [327]

Answer:

The bottom for an A is 75. Round to the nearest whole number as needed.

Step-by-step explanation:

1) Previous concepts

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".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".  

Let X the random variable that represent the scores on this case, and for this case we know the distribution for X is given by:

X \sim N(\mu=73,\sigma=7)  

And let \bar X represent the sample mean, the distribution for the sample mean is given by:

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

2) The bottom for an A is _____. Round to the nearest whole number as needed.

And we want the top 5.5% of the scores, so we need a value a such that:

P(X>a)=0.055 or P(X

We need on the right tail of the distribution a value a that gives to us 94.5% of the area below and 5.5% of the area above. Both conditions are equivalent.

Let's use the condition P(X, the best way to solve this problem is using the z score with the following formula:

z=\frac{x-\mu}{\sigma}

So we need a value from the normal standard distribution that accumulates 0.945 of the area on the left and 0.055 on the right. This value on this case is 1.598 and we can founded with the following code in excel:

"=NORM.INV(0.945,0,1)"

If we apply the z score formula to our case we have this:

P(X

So then based on the equalities we have this:

\frac{a-73}{7}=1.598

And if we solve for a we got:

a=(7*1.598) +73=84.186

So then we need a score of 84.186 rounded to the nearest whole number 75 or higher in order to get an A

8 0
3 years ago
The product of two numbers is 240. The first number is 8 less than the second number. Write an equation can be used to find x
DaniilM [7]

Answer:

The equation x = y-8

The equation  (y-8) y = 240

The first number x = 12 and second number y =20

Step-by-step explanation:

<u>Explanation</u>:-

<u>Step(l)</u>:-

Let 'x' be the first number and 'y' be the second number

Given the product of two numbers is 240

Given  data        x y = 240 …(l)

Given data the first number is 8 less than the second number.

                       x = y-8...(ll)

Substitute (ll) in equation (l) , we get

                           (y-8) y = 240

                           y^{2} -8y -240 =0

                            y^{2} -20y+12y -240 =0

                           y(y -20)+12(y -20) =0

                           (y +12)(y -20) =0

                          y = -12 and y = 20

              Y= -12 is not satisfied

              we can choose y = 20

<u>Step(ll):</u>-

Given data x =y-8

  substitute value y = 20 in x = y -8

                                             x = 20-8 = 12

<u>Final answer</u>:-

The first number x = 12 and second number y =20

4 0
3 years ago
The police in a certain city are investigating whether the proportion of minor traffic accidents is greater on Friday nights tha
Ganezh [65]
What city lol? sorry i just need to answer so i can ask question bc i’m lost lol
8 0
3 years ago
At 9:00 pm bob leaves his home and starts walking to the bus stop at a constant speed of 9.3 feet per second. bob's house is 432
klio [65]
a. define variables for the quantities that are changing (be specific).
 We define variables:
 t = time in second
 d = distance traveled
 The variables that are changing are t and d.
 As the time increases, the distance decreases.

 b. what does it mean to say bob walks at a constant speed of 9.3 feet per second?
 It means that for every second that passes, Bob walks 9.3 feet.

 c. consider the formula d = 4320 - 9.3t i. what does t represent? ii. what does 9.3t represent? iii. what does d represent? 
 For this case we have:
 t = represents the time in seconds
 9.3t = represents the distance traveled by Bob
 d = represents the distance Bob must travel to get to the bus stop.
5 0
3 years ago
Use rounding or compatible numbers to estimate the sum 271 + 425
zysi [14]

Answer:

700

Step-by-step explanation:

For this one I'll do estimates. 271 estimated would drop down to 270. And 425 would bump up to 430. Adding 270 and 400 you would get a round number of 700!

Hope this helped.

4 0
3 years ago
Read 2 more answers
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