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3 years ago

15

A drilling machine can drill 12 holes in 6 minutes. If the machine drills holes at a constant speed, it can drill ______ holes i

n 25 minutes.

2 answers:

raketka [301]3 years ago

8 0

I think its 50 because if you split 6 into 12 you get half the amount therefore it can drill 2 holes per minute

Lelu [443]3 years ago

6 0

Probably 50 holes in 25 minutes

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The original price is $60.The sales price is $45. What is the percent of discount?

MariettaO [177]

Hey there!

To start, first subtract 45 from 60 to find the amount of money taken off from the discount:
60-45
=15

Because 15 dollars have been taken off the original price, you can find the percent of discount by setting up this proportion where x represents the percent of discount:
15/60=x/100

Now, cross multiply and solve for x:
1500=60x
x=25

Therefore, your discount would be 25%.

Hope this helps and have a marvelous day! :)

5 0

3 years ago

Say that you own property with a market price of $74,000. The state tax assessors have given it an assessed value of 48% of that

BigorU [14]

Answer:

A

Step-by-step explanation:

74,000 x .48 = 35520. 35520 is the amount of property you have to pay for.

35520 x 0.031 = 1,101.12. 1.101.12 is the amount you owe in property tax.

5 0

3 years ago

It is known that the life of a particular auto transmission follows a normal distribution with mean 72,000 miles and standard de

scoray [572]

Answer:

a) $P(X$

$P(z$

b) $P(X>65000)=P(\frac{X-\mu}{\sigma}>\frac{65000-\mu}{\sigma})=P(Z>\frac{65000-72000}{12000})=P(z>-0.583)$

$P(z>-0.583)=1-P(Z$

c) $P(X>100000)=P(\frac{X-\mu}{\sigma}>\frac{100000-\mu}{\sigma})=P(Z>\frac{100000-72000}{12000})=P(z>2.33)$

$P(z>2.33)=1-P(Z$

Sicne this probability just represent 1% of the data we can consider this value as unusual.

d) $z=1.28$

And if we solve for a we got

$a=72000 +1.28*12000=87360$

So the value of height that separates the bottom 90% of data from the top 10% is 87360.

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Part a

Let X the random variable that represent the life of a particular auto transmission of a population, and for this case we know the distribution for X is given by:

$X \sim N(72000,12000)$

Where $\mu=72000$ and $\sigma=12000$

We are interested on this probability

$P(X$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(X$

And we can find this probability using excel or the normal standard table and we got:

$P(z$

Part b

$P(X>65000)$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(X>65000)=P(\frac{X-\mu}{\sigma}>\frac{65000-\mu}{\sigma})=P(Z>\frac{65000-72000}{12000})=P(z>-0.583)$

And we can find this probability using the complement rule and excel or the normal standard table and we got:

$P(z>-0.583)=1-P(Z$

Part c

$P(X>100000)$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(X>100000)=P(\frac{X-\mu}{\sigma}>\frac{100000-\mu}{\sigma})=P(Z>\frac{100000-72000}{12000})=P(z>2.33)$

And we can find this probability using the complement rule and excel or the normal standard table and we got:

$P(z>2.33)=1-P(Z$

Sicne this probability just represent 1% of the data we can consider this value as unusual.

Part d

For this part we want to find a value a, such that we satisfy this condition:

$P(X>a)=0.1$ (a)

$P(X$ (b)

Both conditions are equivalent on this case. We can use the z score again in order to find the value a.

As we can see on the figure attached the z value that satisfy the condition with 0.9 of the area on the left and 0.1 of the area on the right it's z=1.28. On this case P(Z<1.28)=0.9 and P(z>1.28)=0.1

If we use condition (b) from previous we have this:

$P(X$

$P(z$

But we know which value of z satisfy the previous equation so then we can do this:

$z=1.28$

And if we solve for a we got

$a=72000 +1.28*12000=87360$

So the value of height that separates the bottom 90% of data from the top 10% is 87360.

5 0

3 years ago

eduard

Athe answer is -2 because it is behind the 0 and will be negative and it is two lines away from the 0 so the answer is -2

3 0

3 years ago

SOMEONE PLEASE HELP WILL MARK BRAINLIEST PLEASE EXPLAIN

zalisa [80]

Answer:

a. (x+5)^2 = 49

b. (x+7)^2 = (x+1)^2

Step-by-step explanation:

So the term "a number" is always going to be x. input x into the sentences. "X plus five, then squared, is forty-nine". when they do "is __", that means equal to. In the second question, seven more than x is x + 7 (the two numbers are interchangeable here). Equivalent also means equal. hope this helped :)

4 0

3 years ago

Read 2 more answers