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2 years ago

If there are 40% of girls and 250 are boys, find

Mathematics

1 answer:

oee [108]2 years ago

8 0

Step-by-step answer:

If there are 40% students that are girls , and the rest are 250 boys. Then that must mean there are 60% boys. Because that is the compliment.

Because we know that 60% of the people in the group are boys, and that the amount of boys amounts to 250, we can model an equation like this.

$Total * 0.6 = 250$ .

$Total = 250/0.6$

$Total = 417$

There are 417 students

ii)

Because we know that the total amount is 417, we can find the amount of girls there are by multiplying the total by the percentage.

$417 * 0.4 = 167$

There are 167 students that are girls.

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GreenBeam Ltd. claims that its compact fluorescent bulbs average no more than 3.50 mg of mercury. A sample of 25 bulbs shows a m

Harrizon [31]

Answer:

(a) Null Hypothesis, $H_0$ : $\mu \leq$ 3.50 mg

Alternate Hypothesis, $H_A$ : $\mu$ > 3.50 mg

(b) The value of z test statistics is 2.50.

(c) We conclude that the average mg of mercury in compact fluorescent bulbs is more than 3.50 mg.

(d) The p-value is 0.0062.

Step-by-step explanation:

We are given that Green Beam Ltd. claims that its compact fluorescent bulbs average no more than 3.50 mg of mercury. A sample of 25 bulbs shows a mean of 3.59 mg of mercury. Assuming a known standard deviation of 0.18 mg.

Let $\mu$ = average mg of mercury in compact fluorescent bulbs.

So, Null Hypothesis, $H_0$ : $\mu \leq$ 3.50 mg {means that the average mg of mercury in compact fluorescent bulbs is no more than 3.50 mg}

Alternate Hypothesis, $H_A$ : $\mu$ > 3.50 mg {means that the average mg of mercury in compact fluorescent bulbs is more than 3.50 mg}

The test statistics that would be used here One-sample z test statistics as we know about the population standard deviation;

T.S. = $\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }$ ~ N(0,1)

where, $\bar X$ = sample mean mg of mercury = 3.59

$\sigma$ = population standard deviation = 0.18 mg

n = sample of bulbs = 25

So, test statistics = $\frac{3.59-3.50}{\frac{0.18}{\sqrt{25} } }$

= 2.50

The value of z test statistics is 2.50.

Now, P-value of the test statistics is given by;

P-value = P(Z > 2.50) = 1 - P(Z $\leq$ 2.50)

= 1 - 0.9938 = 0.0062

Now, at 0.01 significance level the z table gives critical value of 2.3263 for right-tailed test. Since our test statistics is more than the critical values of z, so we have sufficient evidence to reject our null hypothesis as it will fall in the rejection region due to which we reject our null hypothesis.

Therefore, we conclude that the average mg of mercury in compact fluorescent bulbs is more than 3.50 mg.

6 0

3 years ago

The length of the shadow of a building is 150 meters, as shown below: The shadow of a building is 150 meters long. The acute ang

mafiozo [28]

So first you want to draw out you triangle and label everything so side a would be x, side b would be 15 and c would be x
next the angles need to be label
and finally the anwser is 150m

3 0

3 years ago

Read 2 more answers

there are 13 animals in the barn. some are chickens and some are goats. there are 48 legs in all. how many of each animal are th

romanna [79]

Answer:

Step-by-step explanation:

chickens + goats = 13

so...

c + g = 13, so...

g = (13 - c)

2 legs times the number of chickens (2c) + 4 legs times the number of goats (4g) = 48 total legs. So...

2c + 4(13-c) = 48, so

2c + 52 - 4c = 48, so

-2c = -4, so

2c = 4, so

c = 2.

There are 2 chickens, and therefore 11 goats.

5 0

3 years ago

- 7 and 8 What’s the answer

kvv77 [185]

Answer:

Step-by-step explanation:

8-7= 1

Hope this helps!

3 0

3 years ago

Use the equation xy= 12.6. Find the value of y when x=7

Marat540 [252]

Answer: y = 1.8

Step-by-step explanation:

xy = 12.6 If x is 7 but 7 in the equation for x

7y = 12.6 Divide both sides by 7

y = 1.8

6 0

3 years ago