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3 years ago

9

Joan puts $400 into a bank account. Each year the account earns 7% simple interest. How much interest will be earned in four yea

rs ?
$60
$72
$84
$112

1 answer:

Sladkaya [172]3 years ago

3 0

$60

400 ÷ 7 = 57. 1428571429

Since that's not an option we estimate it. The closest number is $60 so, there's your answer!

I hope this helps! sorry if it's wrong :(

~ Kana ^^

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A box of cookies cost $2 before tax. Find the after-tax cost if the sales tax was 8.5%.

adell [148]

Answer:

$2.17 total

Step-by-step explanation:

2 (0.85) = v2.17

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3 years ago

Please help i need to find the constant of proportionality

abruzzese [7]

Answer:

4

Step-by-step explanation:

y = 4*x

y = 4*1.5 = 6

y = 4*2.25 = 9

y = 4* 3.25 = 13

3 0

2 years ago

Can anyone please help me with this? i need a step by step explanation please! very appreciated:)

EastWind [94]

Answer:

Step-by-step explanation:

x and y are variables. That means they represent numbers that are unknown. When we solve for x or y, we are trying to find what number the variable represents.

Y is a number that equals both 5x-9 and 3x+7. If it is a number, it can only have one value, so we can say that 5x-9 and 3x+7 have the same value.

In other words, 5x-9 = 3x+7.

Another way of thinking about this step is substitution. y=3x+7, so in the equation y=5x-9, we can replace the y with 3x+7. It will give 3x+7 = 5x-9.

In either case, we have this new equation

5x-9 = 3x+7.

From here it's just simple algebra- subtract 3x from each side

2x -9 = 7

and add 9 to each side

2x = 16

and divide each side by 2.

x = 8.

All these steps work because if two things equal each other, when you do the same thing to both of them (such as add 9), the new values will still equal each other.

Now that we know that x = 8, we can take one of the original equations

y=5x-9

and put 8 in for x.

y=5*(8) -9.

If x represents the value 8, we can obviously switch out x for 8.

Now simplify

y=40 -9

y = 31

Now we know that x = 8 and y = 31.

5 0

3 years ago

Read 2 more answers

Please help! 10 points, thank you

Tpy6a [65]

Answer:

261.5 ft^2

Step-by-step explanation:

Surface Area of a rectangular prism = Length x Width x Height

= 8.5ft x 6ft x 5.5ft

= 261.5 ft

5 0

3 years ago

2. In your own words, explain HOW to find the standard deviation of this data set. (20 points) 3. What does the standard deviati

Ket [755]

Answer:

$\sigma = 11.28$ --- Standard deviation

Step-by-step explanation:

Given

See attachment for graph

Solving (a): Explain how the standard deviation is calculated.

<u>Start by calculating the mean</u>

To do this, we divide the sum of the products of grade and number of students by the total number of students;

i.e.

$\bar x = \frac{\sum fx}{\sum f}$

So, we have:

$\bar x = \frac{50 * 1 + 57 * 2 + 60 * 4 + 65 * 3 +72 *3 + 75 * 12 + 77 * 10 + 81 * 6 + 83 * 6 + 88 * 9 + 90 * 12 + 92 * 12 +95 * 2 + 99 * 4 + 100 * 5}{1 + 2 + 4 + 3 +3 + 12 + 10 + 6 + 6 + 9 + 12 + 12 +2 + 4 + 5}$

$\bar x = \frac{7531}{91}$

$\bar x = 82.76$

Next, calculate the variance using the following formula:

$\sigma^2 = \frac{\sum f(x - \bar x)^2}{\sum f}$

i.e subtract the mean from each dataset; take the squares; add up the squares; then divide the sum by the number of dataset

So, we have:

$\sigma^2 = \frac{1 * (50 - 82.76)^2 +...................+ 5 * (100 - 82.76)^2}{91}$

$\sigma^2 = \frac{11580.6816}{91}$

$\sigma^2 = 127.26$

Lastly, take the square root of the variance to get the standard deviation

$\sigma = \sqrt{\sigma^2}$

$\sigma = \sqrt{127.26}$

$\sigma = 11.28$ --- approximated

<em>Hence, the standard deviation is approximately 11.28</em>

Considering the calculated mean (i.e. 82.76), the standard deviation (i.e. 11.28) is small and this means that the grade of the students are close to the average grade.

8 0

2 years ago