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solong [7]
2 years ago
12

Normal with a mean of 70 minutes and a standard deviation of 10 minutes. Using the 68-95-99.7 rule, what percentage of students

will complete the exam in under an hour?
Mathematics
1 answer:
lys-0071 [83]2 years ago
4 0
Note that 60=70-10\times1, i.e. a student that completes the exam in one hour falls exactly one standard deviation (in the negative direction) from the mean.

Now, you're looking for the proportion of students that fall below this, i.e. \mathbb P(Z. The empirical rule states that approximately 68% of a normal distribution falls within one standard deviation of the mean. That is,

\mathbb P(|Z|

This means that the proportion of students that fall outside this range is

\mathbb P(|Z|>1)=\mathbb P(Z1)=1-\mathbb P(|Z|

Because the distribution is symmetric, it follows that

\mathbb P(Z1)=\dfrac{0.32}2=0.16

This means the percentage of students that complete the exam in under an hour is 16%.
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Would really appreciate the help, can't seem to figure out the answer;-;​
Dafna11 [192]

Answer:

-1*70

Step-by-step explanation:

-1*70=-71

7 0
3 years ago
For the functions f(x)=2x^2+3x+9 and g(x)=−3x+10 find (f⋅g)(x) and (f⋅g)(1)
pashok25 [27]

Step-by-step explanation:

f(x)=2x²+3x+9

g(x) = - 3x + 10

In order to find (f⋅g)(1) first find (f⋅g)(x)

To find (f⋅g)(x) substitute g(x) into f(x) , that's for every x in f (x) replace it by g (x)

We have

(f⋅g)(x) = 2( - 3x + 10)² + 3(- 3x + 10) + 9

Expand

(f⋅g)(x) = 2( 9x² - 60x + 100) - 9x + 30 + 9

= 18x² - 120x + 200 - 9x + 30 + 9

Group like terms

(f⋅g)(x) = 18x² - 120x - 9x + 200 + 30 + 9

(f⋅g)(x) = 18x² - 129x + 239

To find (f⋅g)(1) substitute 1 into (f⋅g)(x)

That's

(f⋅g)(1) = 18(1)² - 129(1) + 239

= 18 - 129 + 239

We have the final answer as

<h3>(f⋅g)(1) = 128</h3>

Hope this helps you

3 0
3 years ago
Charlotte and Edgar's ages add up to 22. Charlotte is one year
nadya68 [22]

Answer: Charlotte's 15 and Edgar's 7

Step-by-step explanation:

7*2=14

14+1 = 15

15 + 7 = 22

8 0
2 years ago
How can you add and subtract rational expression
Elis [28]

Answer:

who knows what your saying

8 0
2 years ago
Read 2 more answers
fred has two types of peanut butter,three types of jelly, and one type of bread. how many different peanut butter and jelly sand
nydimaria [60]

Answer:

6

Step-by-step explanation:

fred has 2 peanut butter and 3 jelly

type 1 peanut butter can go with all three types of jelly = 3 pb&js where ther is one constant peanutbutter and 3 different jellys

type 2 peanut butter can go with all three jellies = 3 pb&js where there is one constant peanutbutter and 3 different jellies

3+3=6

there are 6 peanut butter and jelly sandwhiches he could make.

you can also just multiply the numbers (2x3=6)

8 0
3 years ago
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