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3 years ago

There are 40 boys in a computer club. The ratio of girls to boys is 2 to 5. How many girls are in the club?

Mathematics

2 answers:

Serggg [28]3 years ago

7 0

Answer:

50x2 =100

So the final box is 50x2 = 100

Step-by-step explanation:

There is a pattern in this table. 5, 2, and 2. Ex. 2x5=10, 10x2 =20 on top

The pattern is the same on the bottom: 5x5 =25, 25x2=50, and 50x2 =100

So the final box is 50x2 = 100

Mandarinka [93]3 years ago

4 0

Set up a proportion. 2/5 = x/40
to solve the equation first cross multiply.
x*5=40*2
x*5=80
now divide both sides by 5, 80 divided by 5 is equal to 16.
so the number of girls in the computer lab is 16.

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natta225 [31]

Answer:

a) 99% of the sample means will fall between 0.933 and 0.941.

b) By the Central Limit Theorem, approximately normal, with mean 0.937 and standard deviation 0.0015.

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 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) If the true mean is 0.9370 with a standard deviation of 0.0090 within what interval will 99% of the sample means fail?

Samples of 34 means that $n = 34$

We have that $\mu = 0.937, \sigma = 0.009$

By the Central Limit Theorem, $s = \frac{0.009}{\sqrt{34}} = 0.0015$

Within what interval will 99% of the sample means fail?

Between the (100-99)/2 = 0.5th percentile and the (100+99)/2 = 99.5th percentile.

0.5th percentile:

X when Z has a pvalue of 0.005. So X when Z = -2.575.

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

By the Central Limit Theorem

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

$-2.575 = \frac{X - 0.937}{0.0015}$

$X - 0.937 = -2.575*0.0015$

$X = 0.933$

99.5th percentile:

X when Z has a pvalue of 0.995. So X when Z = 2.575.

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

$2.575 = \frac{X - 0.937}{0.0015}$

$X - 0.937 = 2.575*0.0015$

$X = 0.941$

99% of the sample means will fall between 0.933 and 0.941.

(b) If the true mean 0.9370 with a standard deviation of 0.0090, what is the sampling distribution of ¯X?

By the Central Limit Theorem, approximately normal, with mean 0.937 and standard deviation 0.0015.

6 0

3 years ago

The ordered pair (a, b) gives the location of point P on the coordinate plane. The value of b is negative. The value of a is not

sergejj [24]

Answer:

Quadrant III ( C )

Quadrant IV ( D )

Step-by-step explanation:

Ordered pair ( a, b )

gives a point P on the coordinate plane

( a, b ) = ( x, y )

given : b = negative ( y-axis )

a ≠ 0 ( i.e. a = negative or positive ) ( x -axis )

Therefore point P is located in the : Third and fourth quadrants

8 0

3 years ago

Read 2 more answers

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irina [24]

Retail price
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3 years ago

Dr. Betz, a vet, is running a free rabies clinic. He estimates that it will take him 12 minutes for each animal he treats. Dr. B

Olin [163]

Answer:

equation: y = 12x

Dr. Betz worked for 8 hours.

Step-by-step explanation:

To write the equation we'll use the form y = mx, where y represents the amount of time the Doctor worked, m is the amount of minutes it takes to treat each animal, and x is how many animals have been treated. We know the value of m is 12, so let's put that into the equation:

y = 12x

Now we have our equation. We can use it to see how long Dr. Betz worked. He treated a total of 40 animals - 20 including the shaggy dog, and 20 after the shaggy dog. let's replace x with 40:

y = 12(40)

Now solve:

y = 480

Dr. Betz worked for 480 minutes. There are 60 minutes in an hour. Divide 480 by 60 to find out how many hours Dr. Betz worked for:

480/60 = 8

Dr. Betz worked for 8 hours.

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