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2 years ago

A survey of 225 students showed the mean number of hours spent studying per week was 20.6 and the standard deviations was 2.7

Mathematics

2 answers:

Step2247 [10]2 years ago

6 0

Answer:

.3 is the answer.

Step-by-step explanation:

LekaFEV [45]2 years ago

5 0

Answer:

The margin of error is approximately 0.3

Step-by-step explanation:

The following information has been provided;

The sample size, n =225 students

The sample mean number of hours spent studying per week = 20.6

The standard deviation = 2.7

The question requires us to determine the margin of error that would be associated with a 90% confidence level. In constructing confidence intervals of the population mean, the margin of error is defined as;

The product of the associated z-score and the standard error of the sample mean. The standard error of the sample mean is calculated as;

$\frac{sigma}{\sqrt{n} }$

where sigma is the standard deviation and n the sample size. The z-score associated with a 90% confidence level, from the given table, is 1.645.

The margin of error is thus;

$1.645*\frac{2.7}{\sqrt{225}}=0.2961$

Therefore, the margin of error is approximately 0.3

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An agency that hires out clerical workers claims its workers can type, on average, at least 60 words per minute (wpmwpm). To tes

lapo4ka [179]

Answer:

The right answer is:

If the mean typing speed of workers from the agency is 60 wpmwpm, the probability of selecting a sample of 50 workers with mean 58.8 wpmwpm or less is 0.267.

Step-by-step explanation:

The P-value gives us the probability of getting the sample we are evaluating (in this case a sample with size n=50 and mean=58.8 wpm), if the null hypothesis is true (in this case, μ=60 wpm).

If the P-value is low enough, that is under the significance level, then we can infer that the mean that the null hypothesis states is not the actual mean, and we have evidence to reject the null hypothesis.

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2 years ago

to eliminate the y-terms and solve for x in the fewest steps, by which constants should the equations be multiplied? first equat

Mazyrski [523]

Answer: The first equation should be multiplied by 9 and the second equation by −4, to eliminate the y-terms and solve for x in the fewest steps.

Step-by-step explanation:

Given : Equation (1) 5x − 4y = 28

Equation (2) 3x - 9y = 30

to eliminate the y-terms and solve for x in the fewest steps, we should multiply equation (1) by 9 and equation (2) by -4 such that

9(5x − 4y) =9 (28)⇒45x-36y=252

-4(3x - 9y) = -4(30)⇒ -12x+36y= -120

Now adding both equations, y-term eliminated and we get, 45x-12x=132

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2 years ago

Read 2 more answers

Simplify!!! I need help please

satela [25.4K]

Answer:

$\frac{4^{21}}{5^{6}}$

Step-by-step explanation:

$\frac{4^{7*3}}{5^{2*3}}=\frac{4^{21}}{5^{6}}$

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2 years ago

For customers purchasing a refrigerator at a certain appliance store, let A be the event that the refrigerator was manufactured

kati45 [8]

The answers are the following:
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P(B|A)=0.9
P(B|A′)=0.8
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4 0

2 years ago

Estimate the indicated probability by using normal distribution as an approximation to the binomial distribution. Estimate P(6)

lianna [129]

Answer:

P(6) = 0.6217

Step-by-step explanation:

To find P(6), which is the probability of getting a 6 or less, we will need to first calculate two things: the mean of the sample (also known as the "expected value") and the standard deviation of the sample.

Mean = np

Here, "n" is the sample size and "p" is the probability of the outcome of interest, which could be getting a heads when a tossing a coin, for instanc

So, Mean = n × p = (18) ×(0.30) = 5.4

Next we we will find the standard deviation:

Standard Deviation = $\sqrt{npq}$

n = 18 and p = 0.3 "q" is simply the probability of the other possible outcome (maybe getting a tails when flipping a coin), so q = 1 - p

Standard Deviation = $\sqrt{npq} = \sqrt{(18)(0.3)(0.7)}$

= 1.944

Now calculate the Z score for 6 successes.

Z = ( of successes we're interested in - Mean) ÷ (Standard Deviation)

=(6-5.4) ÷ (1.944) = 0.309

we have our Z-score, we look on the normal distribution and find the area of the curve to the left of a Z value of 0.309. This is basically adding up all of the possibilities for getting less than or equal to 6 successes. So, we get 0.6217.

5 0

2 years ago