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Mama L [17]
2 years ago
7

A store had 5 packs of paper for $7.80. How much would it cost if you were to buy 3 packs

Mathematics
1 answer:
valentina_108 [34]2 years ago
4 0
To buy 3 packs, the cost would be $4.68
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A researcher reports survey results by stating that the standard error of the mean is 25 the population standard deviation is 40
bezimeni [28]

Answer:

a) A sample of 256 was used in this survey.

b) 45.14% probability that the point estimate was within ±15 of the population mean

Step-by-step explanation:

This question is solved using the normal probability distribution and the central limit theorem.

Normal probability distribution

When the distribution is normal, we use the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean \mu and standard deviation \sigma, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean \mu and standard deviation s = \frac{\sigma}{\sqrt{n}}.

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

a. How large was the sample used in this survey?

We have that s = 25, \sigma = 400. We want to find n, so:

s = \frac{\sigma}{\sqrt{n}}

25 = \frac{400}{\sqrt{n}}

25\sqrt{n} = 400

\sqrt{n} = \frac{400}{25}

\sqrt{n} = 16

(\sqrt{n})^2 = 16^2[tex][tex]n = 256

A sample of 256 was used in this survey.

b. What is the probability that the point estimate was within ±15 of the population mean?

15 is the bounds with want, 25 is the standard error. So

Z = 15/25 = 0.6 has a pvalue of 0.7257

Z = -15/25 = -0.6 has a pvalue of 0.2743

0.7257 - 0.2743 = 0.4514

45.14% probability that the point estimate was within ±15 of the population mean

3 0
3 years ago
What does 2*-2-(3- -2) equal
Dovator [93]

Answer:

The value of the expression 2*-2-(3- -2) is -9.

Step-by-step explanation:

2 x (-2)- (3- -2)

=2 x (-2)- (3+2)

=2 x (-2) -5

= -4-5

=<u><em>-9</em></u>

Hope this Helps!!!

Please consider this as brainliest, thanks!!!

8 0
3 years ago
Read 2 more answers
Which ratio is not equivalent to the other three?
strojnjashka [21]
C(12/15) because the other 3 all equal 0.666666666666667 but 12/15 equals 0.8
8 0
3 years ago
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What is<br> 3% of [(-0.5) * (- :)]<br> ?
expeople1 [14]
Solution for 0.5 is what percent of 3:

0.5:3*100 =

(0.5*100):3 =

50:3 = 16.666666666667

Now we have: 0.5 is what percent of 3 = 16.666666666667

Question: 0.5 is what percent of 3?

Percentage solution with steps:

Step 1: We make the assumption that 3 is 100% since it is our output value.

Step 2: We next represent the value we seek with $x$x​.

Step 3: From step 1, it follows that $100\%=3$100%=3​.

Step 4: In the same vein, $x\%=0.5$x%=0.5​.

Step 5: This gives us a pair of simple equations:

$100\%=3(1)$100%=3(1)​.

$x\%=0.5(2)$x%=0.5(2)​.

Step 6: By simply dividing equation 1 by equation 2 and taking note of the fact that both the LHS
(left hand side) of both equations have the same unit (%); we have

$\frac{100\%}{x\%}=\frac{3}{0.5}$
100%
x%​=
3
0.5​​

Step 7: Taking the inverse (or reciprocal) of both sides yields

$\frac{x\%}{100\%}=\frac{0.5}{3}$
x%
100%​=
0.5
3​​

$\Rightarrow x=16.666666666667\%$⇒x=16.666666666667%​

Therefore, $0.5$0.5​ is $16.666666666667\%$16.666666666667%​ of $3$3​.
7 0
2 years ago
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All of the following expressions are equivalent to 12w + 6, except:
laiz [17]
-1(12w - 6) is not equivalent because when the -1 is distributed, the equation becomes -12w + 6, not 12w + 6
5 0
2 years ago
Read 2 more answers
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