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2 years ago

The temperature was 78°F at 3 P.M. Each hour for

Mathematics

1 answer:

polet [3.4K]2 years ago

6 0

Answer:

66 °F

Step-by-step explanation:

At 4 P.M., the temperature had decreased by 3° from the temperature at 3 P.M., so was ...

4 P.M. temp = 78 °F -3° = 75 °F

This was repeated until 7 P.M.

5 P.M. temp = 75 °F -3° = 72 °F

6 P.M. temp = 72 °F -3° = 69 °F

7 P.M. temp = 69 °F -3° = 66 °F

The temperature at 7 P.M. was 66 °F.

Of course the repeated subtraction can be simplified using multiplication. The subtraction of 3° four times is equivalent to the subtraction of . . .

(3°)(4) = 12°

That is, the temperature at 7 P.M. is ...

78 °F -3°×4 = 78 °F -12° = 66 °F

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Janet can get 36-pack of bottled water for $9.60. How much would Janet have to pay for a 12-pack of bottled water if the ratios

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Janet would have to pay $3.20.

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3 years ago

30 children are going on a school trip

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30 × 5 = 150

150 - 110 = 40

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Hope this helped. Have a great day!

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3 years ago

A study of peach trees found that the average number of peaches per tree was 725. The standard deviation of the population is 70

TEA [102]

Answer:

She needs to sample 189 trees.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.025 = 0.975$ , so Z = 1.96.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

The standard deviation of the population is 70 peaches per tree.

This means that $\sigma = 70$

How many trees does she need to sample to obtain an average accurate to within 10 peaches per tree?

She needs to sample n trees.

n is found when M = 10. So

$M = z\frac{\sigma}{\sqrt{n}}$

$10 = 1.96\frac{70}{\sqrt{n}}$

$10\sqrt{n} = 1.96*70$

Dividing both sides by 10:

$\sqrt{n} = 1.96*7$

$(\sqrt{n})^2 = (1.96*7)^2$

$n = 188.2$

Rounding up:

She needs to sample 189 trees.

3 0

3 years ago

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2 years ago

Read 2 more answers

A town in east Texas received 10 inches of rain in two DAYS. If it kept raining at this rate for a 31 day month, how much rain d

nydimaria [60]

<h3>Answer: 155 inches</h3>

This is equivalent to approximately 12.917 feet.

===================================================

Work Shown:

(10 inches)/(2 days) = (x inches)/(31 days)

10/2 = x/31

10*31 = 2*x ... cross multiply

310 = 2x

2x = 310

x = 310/2

x = 155

Keep in mind that this water is being drained on a fairly continuous basis. This means that not all of the water is sticking around (we'd hope not anyway) at the same moment in time.

Note: 155 inches = 155/12 = 12.917 feet approximately.

--------------------------

Alternative method:

If the town got 10 inches in 2 days, this means it rains at a unit rate of 10/2 = 5 inches per day.

Multiply that by 31 days and we get 5*31 = 155 inches of total rain.

3 0

3 years ago