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4 years ago

When adding or subtracting fractions, you must have a ______ denominator.

Mathematics

2 answers:

enot [183]4 years ago

8 0

Answer:

When adding or subtracting fractions,you must have a same or common denominator.

Hope this will help u...

Gemiola [76]4 years ago

7 0

Answer:common

Step-by-step explanation:

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(08.07 LC)

Simora [160]

Answer:

3, -8 , 11.

Step-by-step explanation:

f(x) = (x - 3)(x + 8)(x - 11)

Finding the zeros:

(x - 3)(x + 8)(x - 11) = 0

x - 3 = 0 gives x = 3.

x + 8 = 0 gives x = -8.

x - 11 = 0 gives x = 11.

7 0

3 years ago

Which is true about constructing a bisector of the angle?

IgorLugansk [536]

When you bisect something you are cutting it in half. so in the image above when you cut it in half you would be forming 2 angles. Your answer is D. because when you cut in half you are going to have equal sides. Its like taking an 75 degrees and bisecting it and each of the new angles would be 37.5.

4 0

3 years ago

Solve for x 3+5x=18

Nikitich [7]

Answer:

x=3

Step-by-step explanation:

7 0

3 years ago

Read 2 more answers

In 2010, the Census Bureau estimated the proportion of all Americans who own their homes to be 0.669. An urban economist wants t

Alexxandr [17]

Answer:

Sample size making use of the Census Bureau: 1,499 American adults.

Sample size without making use of the Census Bureau: 1,692 American adults

ii)

Step-by-step explanation:

The sample size n in Simple Random Sampling is given by

$\bf n=\frac{z^2p(1-p)}{e^2}$

where

z = 1.645 is the critical value for a 90% confidence level (*) 

p= 0.669 is the population proportion given by the Census

e = 0.02 is the margin of error

$\bf n=\frac{(1.645)^2*0.669*0.331}{0.02^2}=1,498.05\approx 1,499$

rounded up to the nearest integer.

(*)This is a point z such that the area under the Normal curve N(0,1) 1nside the interval [-z, z] equals 90% = 0.9

It can be obtained with tables or in Excel or OpenOffice Calc with

NORMSINV(0.95)

If she ignores the Census estimate, the she has to take the largest sample possible that meets the requirements.

Let's show it is obtained when p = 0.5

As we said, the sample size n is

$\bf n=\frac{z^2p(1-p)}{e^2}$

where

e = 0.02 is the error proportion

z = 1.645

hence

$\bf n=\frac{(1.645)^2p(1-p)}{(0.02)^2}=6765.0625p(1-p)=6765.0625p-6765.0625p^2$

taking the derivative with respect to p, we get

n'(p)=6765.0625-2*6765.0625p

and

n'(p) = 0 when p=0.5

By taking the second derivative we see n''(p)<0, so p=0.5 is a maximum of n

This means that if we set p=0.5, we get the maximum sample size for the confidence level required for the proportion error 0.02

Replacing p with 0.5 in the formula for the sample size we get

$\bf n=6765.0625*0.5-6765.0625(0.5)^2=1691.27\approx 1,692$

rounded to the nearest integer.

ii)

When we do not have a proportion but a variable whose approximate standard deviation s is known, then the sample size n in Simple Random Sampling is given by

$\bf n=\frac{z^2s^2}{e^2}$

where

z = 2.241 is the critical value for a 95% confidence level (*) 

s = 7.5 is the estimated population standard deviation

e = 2 hours is the margin of error

$\bf n=\frac{z^2s^2}{e^2}=\frac{(2.241)^2(7.5)^2}{(2)^2}=70.62\approx 71$

(*)This is a point z such that the area under the Normal curve N(0,1) inside the interval [-z, z] equals 95% = 0.95

It can be obtained in Excel or OpenOffice Calc with

NORMSINV(0.9875)

5 0

4 years ago

Weekly demand for cell phones at a Best Buy store is normally distributed, with a mean of 300 and a standard deviation of 200. T

ser-zykov [4K]

Answer:

The amount of safety inventory of cell phones best buy should carry is $465.277

Step-by-step explanation:

Solution

We recall that:

The weekly demand for cell phones= 300 per week

The Standard Deviation = 200 per week

The lead time or number of weeks = 2 weeks (14 days)

Thus,

Z = 95%

= 1.645

Now,

The standard deviation of lead time = Standard deviation√ *√ lead time

Which is

= 200 * √ (2) =2.82.843

So,

The safety inventory = Z * Standard deviation of the lead time

= 1.645 * 2.82.843

$465.277

7 0

4 years ago