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2 years ago

Solve this pls thank you

Mathematics

1 answer:

Nana76 [90]2 years ago

5 0

Answer:21

Step-by-step explanation:9+10=21

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The Highway Safety Department wants to study the driving habits of individuals. A sample of 40 cars traveling on a particular st

Ipatiy [6.2K]

Answer:

We need a sample size of at least 101

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:

$\alpha = \frac{1-0.99}{2} = 0.005$

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

So it is z with a pvalue of $1-0.005 = 0.995$ , so $z = 2.575$

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.

What sample size is needed to estimate the true average speed to within 2 mph at 99% confidence?

We need a sample of at least n.

n is found when M = 2. So

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

$2 = 2.575*\frac{7.8}{\sqrt{n}}$

$2\sqrt{n} = 2.575*7.8$

$\sqrt{n} = \frac{2.575*7.8}{2}$

$(\sqrt{n})^{2} = (\frac{2.575*7.8}{2})^{2}$

$n = 100.85$

Rounding up

We need a sample size of at least 101

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3 years ago

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11 A freezer was set at -4.5°F then lost power for 2 hours. In that

sergey [27]

Answer:

-0.8⁰F

You subtract 3.7 from 4.5 and you get 0.8 and you add a negative sign because -4.5 is bigger than positive 3.7

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3 years ago

Help 4/10 as a decimal

Rom4ik [11]

0.4 is 4/10 in decimal form.

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2 years ago

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The local park has 4 bike racks. Each bike rack can hold 15 bikes. There are 16 bikes in the bike racks. What expression shows t

Step2247 [10]

44 that's a tricky question at first i thought it was -1 lol

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3 years ago

There are 134 third graders and 167 fourth graders at the annual school and family picnic. the number of students is 7 times the

grandymaker [24]

I got 39 tables.
134+167=301
301/7=43
Total amount of people =344
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3 years ago