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SOVA2 [1]
3 years ago
15

20 POINTS!!! Mr. Moore is installing new work benches in the wood shop. He wants the height of the benches to be best for studen

ts standing and working on projects. He decides to use the mean height of the students in the school as a guide. The school has 6th, 7th, and 8th grade students. Rather than using the heights of all the students in the school, he decides to take a sample of students.
A: Suppose Mr. Moore decides to use 20 seventh graders as the sample. Is this sample a random sample? Explain your reasoning.

B: Mr. Moore decides to use a random number generator to select 20 students from the school. Suppose that when choosing 20 students using the random generator on the graphing calculator, Mr. Moore’s sample is all eighth graders. Does that mean the sample is not a random sample? Explain your reasoning.
Mathematics
2 answers:
liubo4ka [24]3 years ago
6 0

A: Suppose Mr. Moore decides to use 20 seventh graders as the sample. Is this sample a random sample? Explain your reasoning.

Ans: No, because he only chose the seventh graders which is invalid since he wants to have to use the mean height which involves the 6th, 7th and 8th graders.

B: Mr. Moore decides to use a random number generator to select 20 students from the school. Suppose that when choosing 20 students using the random generator on the graphing calculator, Mr. Moore’s sample is all eighth graders. Does that mean the sample is not a random sample? Explain your reasoning.

Ans: No, it is still a random sample. Since he is using a random generator, there is a possibility that the random generator would pick all students from the 8th grade. Unlike the first one, the random generator is not biased towards any grade, it is just a coincidence.

Viktor [21]3 years ago
3 0

Answer:

A) That's not a random sample because everyone doesn't have an equal chance of being selected

B) It is a random sample. All from eight grade is just a coincidence (which is very unlikely)

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This is wrong and you need to take it down
lesya692 [45]
I don't think I fully understand what you mean.
5 0
3 years ago
Suppose that 50% of all young adults prefer McDonald's to Burger King when asked to state a preference. A group of 12 young adul
ddd [48]

Answer:

a) 0.194 = 19.4% probability that more than 7 preferred McDonald's

b) 0.787 = 78.7% probability that between 3 and 7 (inclusive) preferred McDonald's

c) 0.787 = 78.7% probability that between 3 and 7 (inclusive) preferred Burger King

Step-by-step explanation:

For each young adult, there are only two possible outcomes. Either they prefer McDonalds, or they prefer burger king. The probability of an adult prefering McDonalds is independent from other adults. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}

In which C_{n,x} is the number of different combinations of x objects from a set of n elements, given by the following formula.

C_{n,x} = \frac{n!}{x!(n-x)!}

And p is the probability of X happening.

50% of all young adults prefer McDonald's to Burger King when asked to state a preference.

This means that p = 0.5

12 young adults were randomly selected

This means that n = 12

(a) What is the probability that more than 7 preferred McDonald's?

P(X > 7) = P(X = 8) + P(X = 9) + P(X = 10) + P(X = 11) + P(X = 12)

In which

P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}

P(X = 8) = C_{12,8}.(0.5)^{8}.(0.5)^{4} = 0.121

P(X = 9) = C_{12,9}.(0.5)^{9}.(0.5)^{3} = 0.054

P(X = 10) = C_{12,10}.(0.5)^{10}.(0.5)^{2} = 0.016

P(X = 11) = C_{12,11}.(0.5)^{11}.(0.5)^{1} = 0.003

P(X = 12) = C_{12,12}.(0.5)^{12}.(0.5)^{0} = 0.000

P(X > 7) = P(X = 8) + P(X = 9) + P(X = 10) + P(X = 11) + P(X = 12) = 0.121 + 0.054 + 0.016 + 0.003 + 0.000 = 0.194

0.194 = 19.4% probability that more than 7 preferred McDonald's

(b) What is the probability that between 3 and 7 (inclusive) preferred McDonald's?

P(3 \leq X \leq 7) = P(X = 3) + P(X = 4) + P(X = 5) + P(X = 6) + P(X = 7)

P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}

P(X = 3) = C_{12,3}.(0.5)^{3}.(0.5)^{9} = 0.054

P(X = 4) = C_{12,4}.(0.5)^{4}.(0.5)^{8} = 0.121

P(X = 5) = C_{12,5}.(0.5)^{5}.(0.5)^{7} = 0.193

P(X = 6) = C_{12,6}.(0.5)^{6}.(0.5)^{6} = 0.226

P(X = 7) = C_{12,7}.(0.5)^{7}.(0.5)^{5} = 0.193

P(3 \leq X \leq 7) = P(X = 3) + P(X = 4) + P(X = 5) + P(X = 6) + P(X = 7) = 0.054 + 0.121 + 0.193 + 0.226 + 0.193 = 0.787

0.787 = 78.7% probability that between 3 and 7 (inclusive) preferred McDonald's

(c) What is the probability that between 3 and 7 (inclusive) preferred Burger King?

Since p = 1-p = 0.5, this is the same as b) above.

So

0.787 = 78.7% probability that between 3 and 7 (inclusive) preferred Burger King

7 0
2 years ago
It took 2/3 of an hour to complete her science homework. It took Bethany 3/4 of the amount of time to do her math homework as he
SOVA2 [1]
We know there are 60 minutes in an hour.  To find 2/3 of an hour we divide 60/3 to find 1/3 and multiply by 2 so:
60/3 = 20
20*2 = 40 minutes (which is 2/3 of an hour) to do science

We do the same thing with the 40 minutes.  To find 1/4 of 40 minutes we divide 40 by 4 and then multiply it by 3 to get 3/4 so:

40/4 = 10
10*3 = 30 minutes

Then subtract the times 40-30 = 10 minutes

It took her 10 more minutes to complete her science homework.

Hope that helps


3 0
3 years ago
What are the zeros of f(x) = x2 - 8x+16?
Stels [109]

Answer:

x=4

Step-by-step explanation:

f(x) = x^2 - 8x+16

Set equal to zero

0 = x^2 -8x +16

Factor

what 2 numbers multiply to 16 and add to -8

-4*-4 = 16

-4+-4 = -8

0= (x-4)(x-4)

Using the zero product property

x-4 = 0  x-4 =0

x=4  x=4

3 0
3 years ago
Jose has saved $75 to take tutoring classes. He must pay a registration fee of $15 and then an additional $6 for each class.
bonufazy [111]

Answer:

15+6x=75

Step-by-step explanation:

15 is the starting fee and it is 6$ per class so it would be 6x+15=75

4 0
3 years ago
Read 2 more answers
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