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3 years ago

15

there were 260 students enrolled in a school last year and 40 teachers employed by the same school. this year the number of stud

ents increased by 10% but the number of teachers decreased by 5%. find the percentage change of student per teacher ratio of the school

1 answer:

tatiyna3 years ago

7 0

The percentage change would be 4%

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grain is stored in cylindrical structures called silos which is the best estimate for the volume of a silo with a diameter of 12

zalisa [80]

Volume of a cylinder = base x height
the base is the area of the circle at the bottom.

To find the area of a circle, you use:
A = πr²
where r is the radius of the circle.
radius is half of the diameter, so with a diameter of 12.3, (divide that by 2) the radius of the circle is 6.15 feet.

A = π(6.15)²
A ≈ 118.82

Since we know the height is 25 feet, we can solve for the area of the cylinder.

Area of the cylinder = 118.82 x 25 = 2,970.57 feet cubed

8 0

3 years ago

The owner of a moving company typically has his most experienced manager predict the total number of labor hours that will be re

ValentinkaMS [17]

Answer:

0.9538

Step-by-step explanation:

The computation of the proportion of variation in labor hours is explained by the number of cubic feet moved is shown below:

Here the R^2 coefficient of determination, would be determined and applied the same

R^2 = 1 - SSE ÷ SST

= 1 - 123.97 ÷ 2685.9

= 0.9538

3 0

3 years ago

A simple random sample of 110 analog circuits is obtained at random from an ongoing production process in which 20% of all circu

telo118 [61]

Answer:

64.56% probability that between 17 and 25 circuits in the sample are defective.

Step-by-step explanation:

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

Normal probability distribution

Problems of normally distributed samples can be 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.

When we are approximating a binomial distribution to a normal one, we have that $\mu = E(X)$ , $\sigma = \sqrt{V(X)}$ .

In this problem, we have that:

$n = 110, p = 0.2$

So

$\mu = E(X) = np = 110*0.2 = 22$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{110*0.2*0.8} = 4.1952$

Probability that between 17 and 25 circuits in the sample are defective.

This is the pvalue of Z when X = 25 subtrated by the pvalue of Z when X = 17. So

X = 25

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

$Z = \frac{25 - 22}{4.1952}$

$Z = 0.715$

$Z = 0.715$ has a pvalue of 0.7626.

X = 17

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

$Z = \frac{17 - 22}{4.1952}$

$Z = -1.19$

$Z = -1.19$ has a pvalue of 0.1170.

0.7626 - 0.1170 = 0.6456

64.56% probability that between 17 and 25 circuits in the sample are defective.

4 0

3 years ago

a runner wants to run 1000 miles in one year. if he runs the same number everyday, use compatible numbers to estimate the number

vampirchik [111]

2.73972603 or ... you can round to the nearest tenth... 2.7

7 0

3 years ago

Read 2 more answers

A campground owner has 24002400 m of fencing. he wants to enclose a rectangular field bordering a river, with no fencing along

Free_Kalibri [48]

We define variables:
x = represent the width of the field
y = represent the length of the field
We write the perimeter (with no fencing along the river):
2400 = 2x + y
We clear y:
y = 2400-2x
Answer:
an expression for the length of the field as a function of x is:
y = 2400-2x

4 0

3 years ago