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Feliz [49]
3 years ago
13

Students at university x must be in one of the class ranks, freshman, sophomore, junior, or senior. at university x, 35% of the

students are freshmen and 30% are sophomores. if a student is selected at random, the probability he or she is either a junior or a senior is
Mathematics
1 answer:
miskamm [114]3 years ago
5 0
A student has to be in one of those four ranks.
If a student is not a freshman or sophomore, he must be a junior or a senior.
All students make up 100% of the total number of students.
Since the freshmen are 35% of the students, and the sophomores are 30% of the students, then they make up 65% of all students.
100% - 65% = 35%.
That means the juniors and seniors combined account for 35% of all students.
A student selected randomly has a 35% probability of being a junior or a senior.
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Frank works at a convenience store. He earns 7.50 per hour when he works during the day. He earns 12.50 per hour when he works a
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6) Double a number is equal to the number decreased by five. Find the number.
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Answer:

B) -5

Step-by-step explanation:

let the number be x

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3 years ago
Kevin said that if you triple his age the result will be 1 less than his mother age
Ivahew [28]
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8 0
4 years ago
According to the norms established for a reading comprehension test, eighth-graders should average 83.2 with a standard deviatio
joja [24]

Answer:

t=\frac{86.7-83.2}{\frac{8.6}{\sqrt{45}}}=2.73    

p_v =P(t_{44}>2.73)=0.0045    

If we compare the p value and a significance level given \alpha=0.01 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, so we can conclude that the population mean is signficantly higher than 83.2 at 1% of significance.

Step-by-step explanation:

Data given and notation    

\bar X=86.7 represent the average life for the sample    

s=8.6 represent the population standard deviation    

n=45 sample size    

\mu_o =83.2 represent the value that we want to test    

\alpha=0.01 represent the significance level for the hypothesis test.    

t would represent the statistic (variable of interest)    

p_v represent the p value for the test (variable of interest)    

State the null and alternative hypotheses.    

We need to apply a two tailed  test.  

What are H0 and Ha for this study?    

Null hypothesis:  \mu \leq 83.2  

Alternative hypothesis :\mu > 83.2  

Compute the test statistic  

The statistic for this case is given by:  

t=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}} (1)    

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".    

Calculate the statistic    

We can replace in formula (1) the info given like this:    

t=\frac{86.7-83.2}{\frac{8.6}{\sqrt{45}}}=2.73    

Give the appropriate conclusion for the test  

First we need to calculate the degrees of freedom given by:

df=n-1=45-1=44

Since is a one side right tailed test the p value would be:    

p_v =P(t_{44}>2.73)=0.0045    

Conclusion    

If we compare the p value and a significance level given \alpha=0.01 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, so we can conclude that the population mean is signficantly higher than 83.2 at 1% of significance.

8 0
3 years ago
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