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3 years ago

There are 36 student in Mr. Barrett's math class. If there are 27 girls, what percent of the students are boys?

Mathematics

2 answers:

mafiozo [28]3 years ago

6 0

Subtract 27 from 36 = 9
9/36 = 0.25
To turn a decimal into a percent multiply by 100
25%

25% of the students are boys

Alecsey [184]3 years ago

6 0

36-27=9
9 boys.
9/36=0.25
0.25=25%

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The sum of six number is 33. What is their mean?

lara [203]

Answer:

mean = 33/6 =5.5

Step-by-step explanation:

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3 years ago

Read 2 more answers

Evaluate the expression -7 1/4x + 3 5/8 for x= -4

Misha Larkins [42]

Answer:

32 5/8 (or 32 and 5/8)

Step-by-step explanation:

Okay, so this problem is asking for us to solve this problem with the substitution of a variable: x = -4. Before we fully solve this problem, we need to replace all of those x variables with -4 so that it is easier to solve.

-7 1/4(-4) + 3 5/8.

To make this problem even easier to solve, let's turn these mixed numbers into improper fractions. To do this, multiply the denominator by the whole number. Then add the numerator to this number. The new number that you just got is now your new numerator for this number.

-29/4(-4) + 3 5/8.

Repeat the last step to turn the other mixed number into an improper fraction.

-29/4(-4) + 29/8.

Now let's multiply that -4 by 29/4. Because a whole number technically has a denominator of 1, we can now set up the next part of our problem. (The symbol * means multiplication since we can't use x since it is already being used as a variable in this equation.)

(-29/4 * -4/1) + 29/8.

29 + 29/8.

Now to solve the rest of this problem, let's convert the whole number of 29 so that it has a denominator of 8. This is that these two numbers are addable.

29 x 8 = 232

1 x 8 = 8

Now these numbers are addable. So:

232/8 + 29/8 = 261/8 = 32 5/8.

I hope that this helps.

4 0

2 years ago

Andrew plans to retire in 32 years. He plans to invest part of his retirement funds in stocks, so he seeks out information on pa

Debora [2.8K]

Answer:

a) 0.0885 = 8.85% probability that the mean annual return on common stocks over the next 40 years will exceed 13%.

b) 0.4129 = 41.29% probability that the mean return will be less than 8%

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, 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.

Mean 8.7% and standard deviation 20.2%.

This means that $\mu = 8.7, \sigma = 20.2$

40 years:

This means that $n = 40, s = \frac{20.2}{\sqrt{40}}$

(a) What is the probability (assuming that the past pattern of variation continues) that the mean annual return on common stocks over the next 40 years will exceed 13%?

This is 1 subtracted by the pvalue of Z when X = 13. So

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

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$