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ki77a [65]
2 years ago
15

Type the correct answer in each box. Use numerals instead of words. If necessary, use / for the fraction bar(s). The grades rece

ived by 200 students follow a normal distribution. The mean of the grades is 70%, and the standard deviation is 7%. The number of students who received a grade greater than 70% is about __ , and the number of students who got a grade higher than 84% is about __ .
Mathematics
1 answer:
faltersainse [42]2 years ago
5 0

Answer:

  • 100
  • 5

Step-by-step explanation:

a) The mean of a normal distribution is also the median. Half the population will have values above the mean. Half of 200 is 100, so ...

... 100 students will have grades above 70%.

b) 84% is 14% above the mean. Each 7% is 1 standard deviation, so 14% is 2 standard deviations above the mean. The empirical rule tells you 95% of the population is within 2 standard deviations of the mean, so about 5% of students (10 students) got grades higher than 84% or lower than 56%. The normal distribution is symmetrical, so we expect about 5 students in each range.

... about 5 students will have grades above 84%.

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A music buff wants to estimate the percentage of students at a midwestern university who believe that elvis is still alive. how
gulaghasi [49]
Since we are not given any information about the proportion, we will assume the sample proportion to be 0.50

so,
p = 0.50
The Error is 10% percentage point. This means that on either side of the population proportion the error is 5% so E = 0.05
z = 1.645 (Z value for 90% confidence interval)

The margin of error for population proportion is calculated as:

E=z* \sqrt{ \frac{p(1-p)}{n} }  \\  \\ 
 \frac{E}{z} = \sqrt{ \frac{p(1-p)}{n} }  \\  \\ 
( \frac{E}{z} )^{2}= \frac{p(1-p)}{n} \\  \\ 
n= p(1-p)* (\frac{z}{E})^{2}  \\  \\ 
n=271

This means 271 students should be included in the sample
5 0
2 years ago
The data set below shows the number of books checked out from a library during the first two weeks of the month: 10, 89, 80, 95,
kompoz [17]
I am pretty sure your answer is going to be B, <span>There are two outliers, indicating very few books were rented out on those two days. I hope this helps!! :)</span>
5 0
2 years ago
Read 2 more answers
Sketch the region enclosed by the given curves. Decide whether to integrate with respect to x or y. Draw a typical approximating
MakcuM [25]

Answer:

A=8.4063u^{2}

Step-by-step explanation:

Be the functions:

y=\frac{3}{x};y=\frac{3}{x^{2}}:x=7

according the graph:

\int\limits^1_7 {\frac{3}{x} } \, dx -\int\limits^1_7 {\frac{3}{x^{2} } } \, dx =3\int\limits^1_7 {\frac{1}{x} } \, dx -3\int\limits^1_7 {\frac{1}{x^{2} } } \, dx=3(\int\limits^1_7 {\frac{1}{x} } \, dx -\int\limits^1_7 {\frac{1}{x^{2} } } \, dx)=3[lnx-\frac{1}{x}](1-7)=3[(ln7-ln1)-(\frac{1}{7}-1)]=3[(1.945-0)-(0.1428-1)]=3*(1.945+0.8571)=3*2.8021=8.4063u^{2}

6 0
2 years ago
What is the scale factor of ABC to UVW
Hoochie [10]
One of the easiest question I've seen.
It's a scale factor of 5 because, 
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9 0
2 years ago
Read 2 more answers
According to Masterfoods, the company that manufactures M&amp;M’s, 12% of peanut M&amp;M’s are brown, 15% are yellow, 12% are re
Ipatiy [6.2K]

Answer:

a) 0.88

b) 0.35

c) 0.0144

d) 0.2084

e) 0.7916

Step-by-step explanation:

a) The probability of a peanut being brown is 12/100 = 0.12. Hence the probability of it not being brown is 1-0.12 = 0.88

b) 12% of peanuts are brown, 23% are blue. So 35% are either blue or brown. The probability of a peanut being blue or brown is, therefore 35/100 = 0.35.

c) 12% of peanuts are red, so the probability of a peanut being red is 12/100 = 0.12. In order to calculate the probability of 2 peanuts being both red, we can assume that the proportion doesnt change dramatically after removing one peanut (because the number of peanuts is absurdly high. We can assume that we are replenishing the peanuts). To calculate the probability of 2 peanuts being both red, we need to power 0.12 by 2, hence the probability is 0.12² = 0.0144.

d) Again, we will assume that the probability doesnt change, because we replenish. The probability of a peanut being blue is 0.23. The probability of it not being blue is 0.77, so the probability of 6 peanuts not being blue is obtained from powering 0.77 by 6, hence it is 0.77⁶ = 0.2084

e) The event 'at least one peanut is blue' is te complementary event of 'none peanuts are blue', so the probability of this event is 1- 0.2084 = 0.7916

4 0
2 years ago
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