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2 years ago

12

A student earned a grade of 80% on a math test that had 29 problems. How many problems on this test did the student answer corre

ctly? (Round to the nearest whole number)

2 answers:

KengaRu [80]2 years ago

6 0

He got 23 questions correct out of 29 problems

Andreyy892 years ago

3 0

The student got 23 out of 29 questions correct.

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Consider a normal distribution curve where the middle 85 % of the area under the curve lies above the interval ( 8 , 14 ). Use t

NeTakaya

Answer:

$\mu = 11$

$\sigma = 2.08$

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Middle 85%.

Values of X when Z has a pvalue of 0.5 - 0.85/2 = 0.075 to 0.5 + 0.85/2 = 0.925

Above the interval (8,14)

This means that when Z has a pvalue of 0.075, X = 8. So when $Z = -1.44, X = 8$ . So

$Z = \frac{X - \mu}{\sigma}$

$-1.44 = \frac{8 - \mu}{\sigma}$

$8 - \mu = -1.44\sigma$

$\mu = 8 + 1.44\sigma$

Also, when X = 14, Z has a pvalue of 0.925, so when $X = 8, Z = 1.44$

$Z = \frac{X - \mu}{\sigma}$

$1.44 = \frac{14 - \mu}{\sigma}$

$14 - \mu = 1.44\sigma$

$1.44\sigma = 14 - \mu$

Replacing in the first equation

$\mu = 8 + 1.44\sigma$

$\mu = 8 + 14 - \mu$

$2\mu = 22$

$\mu = \frac{22}{2}$

$\mu = 11$

Standard deviation:

$1.44\sigma = 14 - \mu$

$1.44\sigma = 14 - 11$

$\sigma = \frac{3}{1.44}$

$\sigma = 2.08$

7 0

2 years ago

Michael walked 30 meters in 20 seconds how many meters does he walk per second

Kipish [7]

Answer:

1.5 m/s or 1.5 meters per second

Step-by-step explanation:

Distance/Time=Speed

30m/20s= 1.5 m/s or 1.5 meters per second

6 0

3 years ago

Read 2 more answers

Express 18 as a product of its factors?

Dimas [21]

Answer:

18= 2 x 3 x 3

Step-by-step explanation:

Basically, we branch out 18 into its prime factors. So, the prime factorization of 18 is 18= 2 × 3 × 3. A factor tree is not unique for a given number. Instead of expressing 18 as 2 × 9, we can express 18 as 3 × 6.

7 0

2 years ago

Which of the following is one solution to the expression (ax + b)(cx - d) = 0 ?

V125BC [204]

We know that
if <span>(ax + b)(cx - d) = 0
then
</span><span>(ax + b)= 0-----> ax=-b------> x=-b/a
and
</span><span>(cx - d) = 0-----> cx=d------> x=d/c

therefore

the answer is the option
</span><span>C. -\frac{b}{a}</span>

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3 years ago

I need help with this!!

tresset_1 [31]

Answer:

you would use 85 to find angle 4, because they would add up to 180, so you would subract 85 from 180 to get angle 4

Step-by-step explanation:

5 0

3 years ago