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2 years ago

Which expression is equivalent to 21/15 - 915? A. 12 B. 30 15 c. 125 D. 12 15

Mathematics

2 answers:

zepelin [54]2 years ago

6 0

I think the answer would be C because it was the answer i got when i solved it

dedylja [7]2 years ago

4 0

$\textbf{Heya !}$

the denominators are equal, so subtracting these two fractions is a piece of cake:-

$\sf{\cfrac{21}{15}-\cfrac{9}{15}}$

$\sf{\cfrac{21-9}{15}}$

$\sf{\cfrac{12}{15}}$

`hope it's helpful to u ~

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PLEASE HELP..... I WILL GIVE BRAINLIEST!!

Yakvenalex [24]

For the first part:

Every shirt she grabs, will cost her dollars, so if she grabs 3 shirts, then the cost of the shirts is:

$12+12+12=3(12)$

With the same rationale, if she grabs 2 pairs of jeans, the cost of the jeans is:

$19+19=2(19)$

So, her total is:

$3(12)+2(19)$

If you subtract 3 from the total, then the expression is:

$3(12)+2(19)-3=36+38-3=71$

For the second part:

If she's paying 3 less for each shirt, then the cost of 3 shirts will become:

$(12-3)+(12-3)+(12-3)=3(12-3)$

In the same fashion, for the two jeans:

$(19-3)+(19-3)=2(19-3)$

So the expression for the total cost is:

$3(12-3)+2(19-3)=36-9+38-6=59$

For number three:

The amounts are different because the cost of the total purchase is different than the cost of each element that makes up the total purchase.

For number four:

If you're the owner, you want to give the smallest amount of discount (the one in part 1/a).

So you could clarify by saying there's 3 dollars of the TOTAL purchase's cost.

6 0

3 years ago

A microwave is placed on top of two boxes. One box is 2 feet 9 inches tall, the other box is 4 feet 11 inches tall, and the micr

Liula [17]

The answer for this question would be
12ft and 2in

8 0

3 years ago

Read 2 more answers

The amount of money spent on textbooks per year for students is approximately normal.

Ostrovityanka [42]

Answer:a

$336.04 < \mu < 443.96$

The margin of error will increase

The margin of error will decreases

The 99% confidence interval is $0.4107 < p < 0.4293$

Step-by-step explanation:

From the question we are told that

The sample size $n = 19$

The sample mean is $\= x = \$\ 390$

The standard deviation is $\sigma = \$ \ 120$

Given that the confidence level is 95% then the level of significance is mathematically represented as

$\alpha = 100 - 95$

$\alpha = 5 \%$

$\alpha = 0.05$

Next we obtain the critical value of $\frac{\alpha }{2}$ from the normal distribution table

$Z_{\frac{\alpha }{2} } = 1.96$

The margin of error is mathematically represented as

$E = Z_{\frac{\alpha }{2} } * \frac{\sigma}{\sqrt{n} }$

=> $E = 1.96 * \frac{120}{\sqrt{19} }$

=> $E = 53.96$

The 95% confidence interval is

$\= x - E < \mu < \= x + E$

=> $390 - 53.96 < \mu < 390 - 53.96$

=> $336.04 < \mu < 443.96$

When the confidence level increases the $Z_{\frac{\alpha }{2} }$ also increases which increases the margin of error hence the confidence level becomes wider

Generally the sample size mathematically varies with margin of error as follows

$n \ \ \alpha \ \ \frac{1}{E^2 }$

So if the sample size increases the margin of error decrease

The sample proportion is mathematically represented as

$\r p = \frac{210}{500}$

$\r p = 0.42$

Given that the confidence level is 0.99 the level of significance is $\alpha = 0.01$

The critical value of $\frac{\alpha }{2}$ from the normal distribution table is

$Z_{\frac{\alpha }{2} } = 2.58$

Generally the margin of error is mathematically represented as

$E = Z_{\frac{\alpha }{2} }* \sqrt{ \frac{\r p (1- \r p )}{n} }$

=> $E = 0.42 * \sqrt{ \frac{0.42 (1- 0.42 )}{ 500} }$

=> $E = 0.0093$

The 99% confidence interval is

$\r p - E < p < \r p + E$

$0.42 - 0.0093 < p < 0.42 + 0.0093$

$0.4107 < p < 0.4293$

4 0

4 years ago

Elaine had 5/8 of a pizza left after lunch. She told 5 of her friends that they could share the rest. What fraction of the pizza

Oduvanchick [21]

Answer:

1/8

Step-by-step explanation:

7 0

3 years ago

Read 2 more answers

Use differentials to estimate the amount of metal in a closed cylindrical can that is 26 cm high and 10 cm in diameter if the me

Afina-wow [57]

Answer:

The estimated amount of metal in the can is 87.96 cubic cm

Step-by-step explanation:

We can find the differential of volume from the volume of a cylinder equation given by

$V= \pi r^2 h$

Thus that way we will find the amount of metal that makes up the can.

Finding the differential.

A small change in volume is given by:

$dV =\cfrac{\partial V}{\partial h} dh + \cfrac{\partial V}{\partial r} dr$

So finding the partial derivatives we get

$dV =\pi r^2 dh + \pi 2r h dr$

$dV =\pi r^2 dh + 2\pi r h dr$

Evaluating the differential at the given information.

The height of the can is h = 26 cm, the diameter is 10 cm, which means the radius is half of it, that is r = 5 cm.

On the other hand the thickness of the side is 0.05 cm that represents dr = 0.05 cm, and the thickness on both top and bottom is 0.3 cm, thus dh = 0.3 cm +0.3 cm which give us 0.6 cm.

Replacing all those values on the differential we get

$dV =\pi 5^2 (0.6) + 2\pi (5) (26) (0.05)$

That give us

$V= 28 \pi \, cm^3$

Or in decimal value

$\boxed{dV= 87.96 \, cm^3}$

Thus the volume of metal in the can is 87.96 cubic cm.

6 0

4 years ago