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choli [55]
3 years ago
12

Bethany is working her way through school. She works two part-time jobs for a total of 23 hours a week. Job A pays $5.70 per hou

r, and Job B pays $7.10 per hour. How many hours did she work at each job the week that she made $143.70.
Mathematics
1 answer:
Lady bird [3.3K]3 years ago
8 0

Step-by-step explanation:

x = number of hours A

y = number of hours B

x + y = 23

5.7x + 7.1y = 143.7

from the first equation we get

x = 23 - y

this we use in the second

5.7×(23 - y) + 7.1y = 143.7

131.1 - 5.7y + 7.1y = 143.7

1.4y = 12.6

y = 12.6/1.4 = 9

x = 23 - y = 23 - 9 = 14

she worked 14 hours on job A and 9 hours on job B.

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5. Decide if each of the following statements is true or false. Explain your reasoning in each case.
sertanlavr [38]

Answer:

a. The smaller the sample size, the smaller the margin of error.

False if we see the value for the sample size is on the denominator and if we decrease the value of n then increase the value for the margin of error since the margin of error and the sample size are inversely proportional, with the estimated proportion and the confidence level fixed values.

b. If the margin of error is 0.05 and the observed proportion of red chips is 0.45, then the true population proportion is likely to be between 0.40 and 0.50.

Correct. The confidence interval for the population proportion is given by:

\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}

Or equivalently:

\hat p \pm ME

And if we replace on this case we got:

0.45-0.05=0.40

0.45 +0.05=0.50

So then the true proportion is between 0.4 and 0.5 for this case.

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".  

Solution to the problem

The population proportion have the following distribution  

p \sim N(p,\sqrt{\frac{p(1-p)}{n}})

The margin of error for the proportion interval is given by this formula:  

ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}    (a)  

Now if we analyze the statements one by one we have this:

a. The smaller the sample size, the smaller the margin of error.

False if we see the value for the sample size is on the denominator and if we decrease the value of n then increase the value for the margin of error since the margin of error and the sample size are inversely proportional, with the estimated proportion and the confidence level fixed values.

b. If the margin of error is 0.05 and the observed proportion of red chips is 0.45, then the true population proportion is likely to be between 0.40 and 0.50.

Correct. The confidence interval for the population proportion is given by:

\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}

Or equivalently:

\hat p \pm ME

And if we replace on this case we got:

0.45-0.05=0.40

0.45 +0.05=0.50

So then the true proportion is between 0.4 and 0.5 for this case.

4 0
4 years ago
Pls help me with long division
kondaur [170]

86÷3 =

*The divisor is 3 and the dividend is 86

First step: How many 3's can fit into 8? (8÷3)

8÷3 = 2 r 2

Second step: add a 2 above the eight in the tens place of the answer.

86÷3 = 2_

Third step: multiply 3 x 2; 3 x 2 = 6;

In this step, we put a 6 underneath the 8.

Fourth step: Subtract.

In this step, we subtract 8-6 (=2)

Fifth step: bring down the next number. In this case, it is 6.

In this step, we now have the number 26.

Sixth step: How many 3's can fit into 26? (26÷3)

26÷3 = 8 r 2

Last step: Now put an 8 in the one's place and now we have a remaining 2. That is called the remainder. We put the remainder and represent it as "r". We put r2.

I hope this was easy for you to understand!

6 0
3 years ago
Read 2 more answers
Mine is literally a small question so ANSWER it. How are these two equations related?
lana [24]

Answer:

they are opposites?

Step-by-step explanation:

2x makes x twice as big

while .5 makes x twice as small

not sure but thats what im thinkin

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3 years ago
I need help please giving brainliest!
Alchen [17]

Answer:

acute: D and E

obtuse: A and F

right: B

straight: C

Step-by-step explanation:

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Which set of ordered pairs represents a function ?
CaHeK987 [17]

Answer:

the first one of them is right

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