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Helen [10]
3 years ago
15

Scores from an exam are normally distributed with a mean of 85 and a standard deviation of 5. Suppose 188 students take the exam

. About how many would receive a score above 80?
158 students

60 students

122 students

153 students

Mathematics
2 answers:
charle [14.2K]3 years ago
4 0

The mean is \mu=85 and standard deviation is \sigma=5. Then the variable X\sim N(85,5).

Use substitution Z=\dfrac{X-\mu}{\sigma}=\dfrac{X-85}{5}, then the variable Z\sim N(0,1).

The probability Pr(X>80) can be calculated in the following way:

for X=80, Z=\dfrac{80-85}{5} =-1 and Pr(X>80)=Pr(Z>-1). From the diagram Pr(Z>-1)=0.34+0.34+0.135+0.025=0.84.

Conclusion: if 188 students take the exam, then 188·0.84=157.92 (157) would receive a score above 80

Vesna [10]3 years ago
4 0

158 students is correct on grad point

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–2x + 1 – (–7x + 3) = –4 + 3(x – 2)
natali 33 [55]

Answer:

x = -4

Step-by-step explanation:

–2x + 1 – (–7x + 3) = –4 + 3(x – 2)

-2x + 1 + 7x - 3 = -4 + 3x - 6

-2x + 7x - 3x = -4 - 6 - 1 + 3

2x = -8

x = -8/2

x = -4

8 0
3 years ago
This is Quadratics.<br> (5n−5)(2+2n)
ki77a [65]

Answer: 10n^2 - 10

Step-by-step explanation:

(5n - 5)(2+2n) becomes (5n-5)(2n+2)

= (5n)(2n) + (5n)(2) + (-5)(2n) + (-5)(2)

= 10n^2 - 10

5 0
3 years ago
What is the interval notation for the compound inequality? x is less than or equal to -4 or x is greater than or equal to 5?
Tems11 [23]

x is less than or equal to -4 or x is greater than or equal to 5

x <= -4 or x>= 5

There is no intersection of both inequalities when we graph it in number line So, we write the interval notation separately for each inequality

for x<=-4 , x starts at -4  and goes to -infinity because we have less than symbol. Also we have = sign so we use square brackets

Interval notation is (-∞ , -4]

for x>= 5 , x starts at 5  and goes to infinity because we have greater than symbol. Also we have = sign so we use square bracket at 5

Interval notation is [5 , ∞)

Now combine both notation by a 'U' symbol Union

(-∞ , -4] U [5 , ∞)

5 0
3 years ago
What is 5/3 as a percent
IrinaVladis [17]

Answer:

%167

Step-by-step explanation:

5 divided by 3 is 1.67 so times that by 100 and you get %167

4 0
2 years ago
Read 2 more answers
A number, y, is equal to twice the sum of a smaller number and 3. The larger number is also equal to 5 more than 3 times the sma
RSB [31]

Answer:

A.

Step-by-step explanation:

<em>NOTE: The "larger number" will be referred to as y, and the "smaller number" will be referred to as x.</em>

"A number, y, is equal to twice the sum of a smaller number and 3."

This tells us that we must add our smaller number (x) to 3 within parantheses and then multiply the entire term (x+3) by 2.

y=2(x+3)

"The larger number is also equal to 5 more than 3 times the smaller number."

This tells us that we must multiply 3 against our smaller number (x) and add 5 to it.

y=3x+5

Now, to find your answer, we can put the equations in the same form as the answer choices so as to find an equivalent equation. Lets start with the first equation.

This form calls for us to have our x term first, then our y term, then our constant.

y=2(x+3)\\y=2x+6\\-2x+y=6

Now that we've gotten the equation in that form, we can see that our answer choices hold that our leading co-efficient must be positive, which we can adjust for by dividing both sides by -1.

-2x+y=6\\2x-y=-6

This makes the only possible answer choices (A) and (C).

Now, lets do our second equation. The recipe calls for the same form, again with a positive leading coefficient.

y=3x+5\\-3x+y=5\\3x-y=-5

This is only represented by choices (A) and (B).

Therefore, answer choice (A) is the only one which represents both equations.

7 0
3 years ago
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