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3 years ago

10

The area of a rectangular swimming pool is 360 square feet. If the length of the swimming pool is 9 feet more than its width, fi

nd the length of the pool

1 answer:

Inessa [10]3 years ago

7 0

Answer:

l = 24ft

Step-by-step explanation:

A = lw

360 = (x + 9)(x)

360 = x^2 + 9x

0 = x^2 + 9x - 360

0 = (x + 24)(x - 15)

x ≠ -24 (length cannot be negative)

x = 15

l = 15 + 9

l = 24ft

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The lengths of nails produced in a factory are normally distributed with a mean of 4.84 centimeters and a standard deviation of

Helga [31]

Answer:

Top 3%: 4.934 cm

Bottom 3%: 4.746 cm

Step-by-step explanation:

Problems of normally distributed samples are solved using 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.

In this problem, we have that:

$\mu = 4.84, \sigma = 0.05$

Top 3%

Value of Z when Z has a pvalue of 1 - 0.03 = 0.97. So X when Z = 1.88.

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

$1.88 = \frac{X - 4.84}{0.05}$

$X - 4.84 = 0.05*1.88$

$X = 4.934$

Bottom 3%

Value of Z when Z has a pvalue of 0.03. So X when Z = -1.88.

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

$-1.88 = \frac{X - 4.84}{0.05}$

$X - 4.84 = 0.05*(-1.88)$

$X = 4.746$

8 0

2 years ago

A researcher claims that the variation in the salaries of elementary school teachers is greater than the variation in the salari

guajiro [1.7K]

Answer:

a

The null hypothesis is $H_o : \sigma^2_1 = \sigma^2 _2$

The alternative hypothesis is $H_a : \sigma_1 ^2 > \sigma^2_2$

b

$F_{critical} = 1.8608$

c

$F = 2.9085$

d

The decision rule is

Reject the null hypothesis

e

There is sufficient evidence to support the researchers claim

Step-by-step explanation:

From the question we are told that

The first sample size is $n_1 = 30$

The sample variance for elementary school is $s^2_1 = 8324$

The second sample size is $n_2 = 30$

The sample variance for the secondary school is $s^2_2 = 2862$

The significance level is $\alpha = 0.05$

The null hypothesis is $H_o : \sigma^2_1 = \sigma^2 _2$

The alternative hypothesis is $H_a : \sigma_1 ^2 > \sigma^2_2$

Generally from the F statistics table the critical value of $\alpha = 0.05$ at first and second degree of freedom $df_1 = n_1 - 1 = 30 - 1 = 29$ and $df_2 = n_2 - 1 = 30 - 1 = 29$ is

$F_{critical} = 1.8608$

Generally the test statistics is mathematically represented as

$F = \frac{s_1^2 }{s_2^2}$

=> $F = \frac{8324 }{2862}$

=> $F = 2.9085$

Generally from the value obtained we see that $F > F_{critical }$ Hence

The decision rule is

Reject the null hypothesis

The conclusion is

There is sufficient evidence to support the researchers claim

4 0

2 years ago

A steel company sells 48 tons of steel each year.

ddd [48]

Answer:

16 tons

Step-by-step explanation:

To solve the first step is to change years to months because the time periods are in different units. There are 12 months in 1 year. This means that the company sells 48 tons over 12 months. 4 months is the equivalent of 1/3 of 12 months. This means that we can find the amount sold in 4 months by dividing 48 by 3. 48/3 is 16. Thus, the steel company sells 16 tons in 4 months.

Another way to find the answer is to find the unit rate. The unit rate is how many tons are sold in 1 month. Find this by dividing 48 by 12 because this represents the sales of 1 month. 48/12=4, this means that in 1 month, 4 tons of steel are sold. Next, multiply 4 times 4 to find the amount of steel sold in 4 months. 4 times 4 also gives you the same answer of 16.

6 0

2 years ago

HELP ME ASAP!!!!!!!!

coldgirl [10]

Step-by-step explanation:

a. 6 £/hr

b. 6.8 £/hr.....is this right?

8 0

3 years ago

Read 2 more answers

Find the area under the standard normal curve to the left of

JulijaS [17]

A. z = 0.74
The z-score of 0.74 translates to a percentile of 0.77035. Hence, the area under the standard normal curve to the left of z-score 0.74 is ~0.77.

b. z = -2.16
This z-score translates to a percentile of 0.015386 which is also the numerical value of the area under the curve to the left of the z-score

c. z = 1.02
The percentile equivalent of the z-score above is 0.846. The area is also 0.846.

d. z = -0.15
The percentile equivalent and the area is equal to 0.44.

6 0

3 years ago