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bija089 [108]
2 years ago
11

1. One student was upset with her grade on Test 2 and thought the test was too difficult. In her anger, she said, "There is no w

ay the class average on this test was higher than a C." Can you conclude at a 0.05 level of significance that the average score on Test 2 was no higher than a 79?
Mathematics
1 answer:
Lemur [1.5K]2 years ago
4 0

Answer:

Hypothesis rejected

Step-by-step explanation:

Lets use the t-test since the variance of the population is now known. We need to test the hypothesis that H_0: \mu \leq 79 \text{ vs } H_1: \mu > 79 . This is performed in R as follows:

t.test(tt$Test.2.Score,mu=79,alternative="greater")

One Sample t-test

data: tt$Test.2.Score

t = 2.9238, df = 69, p-value = 0.002337

alternative hypothesis: true mean is greater than 79

95 percent confidence interval:

81.26555 Inf

sample estimates:

mean of x

84.27143

Thus, we reject the null hypothesis and conclude that \mu > 79.

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The height of seaweed of all plants in a body of water are normally distributed with a mean of 10 cm and a standard deviation of
Degger [83]

Answer:

Step-by-step explanation:

Hello!

The variable of interest is:

X: height of seaweed.

X~N(μ;σ²)

μ= 10 cm

σ= 2 cm

You have to find the value of the variable X that separates the bottom 0.30 of the distribution from the top 0.70

P(X≤x)= 0.30

P(X≥x)= 0.70

Using the standard normal distribution you have to find the value of Z that separates the bottom 0.30 from the top 0.70 and then using the formula Z= (X-μ)/σ translate the Z value to the corresponding X value.

P(Z≤z)= 0.30

In the body of the table look for the probability of 0.30 and reach the margins to form the Z value. The mean of the distribution is "0" so below 50% of the distribution you'll find negative values.

z= -0.52

Now you have to clear the value of X:

Z= (X-μ)/σ

Z*σ= X-μ

X= (Z*σ)+μ

X= (-0.52*2)+10= 8.96

The value of seaweed height that divides the bottom 30%  from the top 70% is 8.96 cm

I hope this helps!

7 0
2 years ago
Bob newds to mix 2 cups of orange juice concentrate with 3.5 cups of water to make orange juice.Bobvhas 6 cups of concentrate.Ho
aivan3 [116]
So, Bob needs 2 cups of concentrate (I'll use the variable c to shorten it) for every 3.5 cups of water (w). When he has 6 cups of c, he has three times the original recipe, and therefore we need 3w as well. 

3.5x2=6+1=7. So we need 7 cups of water.

Now, 6 cups of concentrate + 7 cups of water = 13 cups of orange juice.

Bob can make 13 cups of orange juice.

Hope I helped!
8 0
2 years ago
A newly drilled water well produces 50,000 quarts of water per week. With no new water feeding the well, the production drops by
Sveta_85 [38]

Answer:

Total amount of water = 5,200,000

Step-by-step explanation:

Given:

water produced = 50,000 quarts of water per week

Production drop = 5% = 0.05 per year

Number of week in year = 52 week

Find:

Total amount of water

Computation:

Sum = a / r

a = 50,000 x 52

a = 2,600,000

Sum = a / [1-r]

Sum = 2,600,000 / 5%

Sum = 2,600,000 / 0.05

Total amount of water = 5,200,000

5 0
1 year ago
Kita's phone had a fully charged battery. With normal usage her phone will last 18 hours. How much time is left on Kita's phone
oksano4ka [1.4K]

Answer: 2.16 hours

?/18=12%/100

18x12%=218%

218%÷100=2.18 hours

<u></u>

3 0
2 years ago
Damian found that 75% of the total number of teenagers surveyed like pop music. If 150 teenagers like pop music, what is the tot
igor_vitrenko [27]
Okay. To find the number of teens he surveyed, we can write and solve a proportion. Set it up like this: 150/x = 75/100. This is because you’re looking for the amount of students he surveyed and you know the percentage and the number of students that like pop music. 150 is over “x”, because “x” will represent the total number of students surveyed. Now, let’s cross multiply the values. 150 * 100 is 15,000. 75 * x = 75x. 15,000 = 75x. Now, divide each side by 75 to isolate the “x”. 15,000/75 is 200. x = 200. Damian surveyed a total of 200 teenagers.
6 0
2 years ago
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