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elena-s [515]
4 years ago
15

If Jackie were to paint her living room alone it would take five hours. Her sister Violet could do the job in six hours. How lon

g would it take them working together?
Mathematics
1 answer:
yuradex [85]4 years ago
6 0
Find how much work they get done in 1 hour
jackie takes 5 hours to do 1 room, so in 1 hour, she does 1/5 room
voilet take 6 hours to do 1 room so in 1 hour, she does 1/6 room

together, they do 1/5+1/6 room in 1 hour
make common denom
1/5+1/6=6/30+5/30=11/30 in 1 hour
11/30 times time=1 room
times both sides by 30/11
time=30/11 hour
time=2 and 8/11 hour
that is about 2 hours and 44 mins


2 and 8/11 hour or 30/11 hours
You might be interested in
How many times does the graph of 4x = 32 - x2 cross the x-axis?
garik1379 [7]

Answer:

The graph crosses the x-axis 2 times

The solutions are  x = -8  &  x = 4

Step-by-step explanation:

Qaudratics are in the form ax^2 + bx+ c

Where a, b, c are constants

Now, let's arrange this equation in this form:

4x=32-x^2\\x^2+4x-32=0

Where

a = 1

b = 4

c = -32

We need to know the discriminant to know nature of roots. The discriminant is:

D=b^2-4ac

If

  • D = 0 , we have 2 similar root and there is 2 solutions and that touches the x-axis
  • D > 0,  we have 2 distinct roots/solutions and both cut the x-axis
  • D < 0,  we have imaginary roots and it never cuts the x-axis

Let's find value of Discriminant:

D=b^2-4ac\\D=(4)^2 -4(1)(-32)\\D=144

Certainly D > 0, so there are 2 distinct roots and cuts the x-axis twice.

We get the roots/solutions by factoring:

x^2+4x-32=0\\(x+8)(x-4)=0\\x=4,-8

Thus,

The graph crosses the x-axis 2 times

The solutions are  x = -8  &  x = 4

6 0
3 years ago
Read 2 more answers
The U.S. Census Bureau conducts a study to determine the time needed to complete the short form. The Bureau surveys 200 people.
NISA [10]

Answer:

8.2-2.58\frac{2.2}{\sqrt{18}}=6.86    

8.2+2.58\frac{2.2}{\sqrt{18}}=9.54    

So on this case the 90% confidence interval would be given by (6.86;9.54)    And the error is given by:

ME= 2.58\frac{2.2}{\sqrt{18}} =1.338

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

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".

\bar X=8.2 represent the sample mean for the sample  

\mu population mean (variable of interest)

\sigma=2.2 represent the population standard deviation

n represent the sample size  

Solution to the problem

The confidence interval for the mean is given by the following formula:

\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}   (1)

Since the Confidence is 0.90 or 90%, the value of \alpha=0.1 and \alpha/2 =0.005, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.005,0,1)".And we see that z_{\alpha/2}=2.58

Now we have everything in order to replace into formula (1):

8.2-2.58\frac{2.2}{\sqrt{18}}=6.86    

8.2+2.58\frac{2.2}{\sqrt{18}}=9.54    

So on this case the 90% confidence interval would be given by (6.86;9.54)    And the error is given by:

ME= 2.58\frac{2.2}{\sqrt{18}} =1.338

8 0
3 years ago
Read 2 more answers
(question 31) if arc mBC =120 and arc mAD =50 whatis the measure of angle DYC
g100num [7]
<h3>Answer:  D) 95</h3>

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

Explanation:

First, let's calculate angle BYC. This is the angle formed by the chords that subtend the arcs mentioned. This angle faces or is aimed toward the direction of the arcs. To find this angle, we'll average the arc measures like so:

angle BYC = (arcAD + arcBC)/2

angle BYC = (50+120)/2

angle BYC = 170/2

angle BYC = 85 degrees

Then we'll use the idea that angles BYC and DYC are supplementary (aka they form a straight 180 degree angle)

angleBYC + angleDYC = 180

angleDYC = 180 - angleBYC

angleDYC = 180 - 85

angleDYC = 95 degrees

which is why the answer is choice D.

5 0
3 years ago
Mariana runs at a rate of 260 meters per minute.<br><br> How far does she run in 6 minutes?
My name is Ann [436]

Answer:

1560 meters

Step-by-step explanation:

All u had to do was multiply 260 and 6 together and then you get your answer

8 0
3 years ago
There are 8 blue candies, 5 pink candies, 1 white candy, and 6 green candies in a candy jar. You reach in, without looking, and
kupik [55]

Answer:

30%

Step-by-step explanation:

Find the total number of candies in the jar.

8 + 5 + 1 + 6 = 20

The probability of choosing a green candy is 6/20 = 3/10 = .3 = 30%

5 0
3 years ago
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