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3 years ago

Two bricklayers San and Joe are working on your house San can complete the work in 5 hours Joe can complete the work in 3 hours

1 answer:

3 0

Guessing this is a combined work problem??? You forgot to post the question. I can solve for the time it takes them to complete the house together..

1/3 + 1/5 = 1/t
5/15 + 3/15 = 1/t
8/15 = 1/t
15/8 = t
1.875 hrs

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A survey of shoppers is planned to determine what percentage use credit cards. prior surveys suggest 63% of shoppers use credit

Alona [7]

We would need a sample size of 560.

We first calculate the z-score associated. with this level of confidence:
Convert 95% to a decimal: 95% = 95/100 = 0.95
Subtract from 1: 1-0.95 = 0.05
Divide by 2: 0.05/2 = 0.025
Subtract from 1: 1-0.025 = 0.975

Using a z-table (http://www.z-table.com) we see that this is associated with a z-score of 1.96.

The margin of error, ME, is given by:
$ME=z*\sqrt{\frac{\hat{p}(1-\hat{p})}{n}}$

We want ME to be 4%; 4% = 4/100 = 0.04. Substituting this into our equation, as well as our proportion and z-score,
$0.04=1.96\sqrt{\frac{0.63(1-0.63)}{n}}
\\
\\\text{Dividing both sides by 1.96,}
\\
\\\frac{0.04}{1.96}=\sqrt{\frac{0.63(0.37)}{n}}
\\
\\\text{Squaring both sides,}
\\
\\(\frac{0.04}{1.96})^2=\frac{0.63(0.37)}{n}
\\
\\\text{Multiplying both sides by n,}
\\
\\n(\frac{0.04}{1.96})^2=0.63(0.37)
\\
\\n(\frac{0.04}{1.96})^2=0.2331
\\
\\\text{Isolating n,}
\\
\\n=\frac{0.2331}{(\frac{0.04}{1.96})^2}=559.67\approx560$

3 0

3 years ago

Cathy borrows $3280 at 0.3% simple interest per month. When Cathy pays the loan back 9 years later what is the total amount that

Afina-wow [57]

Answer: Simple interest= Principal× rate× time/ 100

Amount= Simple interest + Principal

Step-by-step explanation:

4 0

3 years ago

What’s 40% of $600 ?

Mandarinka [93]

Answer:

$240

Step-by-step explanation:

8 0

3 years ago

Read 2 more answers

A book store has twice as many history books as science books. The store has 81 history and science books altogether how many of

atroni [7]

let h= history books

science books = s

h=2s there are 2 times as many history as science so to get them equal we double the science

h+s=81 there are 81 total history and science books

2s+s=81 substitute 2s for h in the above equation

3s = 81 combine like terms

s = 27

There are 27 science books

h=2s

h=2(27)

h=54

there are 54 history books

4 0

3 years ago

Ellen is excited to learn how to ski. She went to White Peaks Mountain, rented a pair of skis for $45, and took 4 hours of group

Vikentia [17]

Answer:

x=30h

Step-by-step explanation:

First, you need to figure out how much she actually paid for lessons, so you need to subtract 45 from 165.

165-45=120

Now you know she paid 120 dollars in total for lessons.

You know she took four hours of lessons, so you divide 120 by 4.

120/4=30

It takes $30 an hour for lessons.

Now you can form an equation.

Since you know it takes $30 per hour of lessons, it will be 30h.

x is the full amount of money paid

You don't need to add 165-45 to your equation because not everyone will need to rent skis when they come to White Peaks.

Hope this helps!

6 0

2 years ago