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2 years ago

14

In the last month, the ratio between Davis's monthly expenditure and his monthly salary was 3 : 7. What percentage of his monthl

y income did he save last month?

1 answer:

UkoKoshka [18]2 years ago

5 0

Answer: 57%

Step-by-step explanation:

Davis's monthly expenditure and his monthly salary was 3 : 7.

This means that for every $7 he received, he spent $3 out of it.

The amount he saved is therefore:

= 7 - 3

= $4

For every $7 received, he saved $4.

Percent = 4/7

= 57%

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13) -4= -b -1/3b and -23/3= 1/2a + 5/3a

Sergeeva-Olga [200]

-4=-1b-(1/3)b

-4=-(4/3)b

-4/-(4/3)=b

b=3

-------------------------------

(1/2)3+(5/3)2

3/6+10/6=13/6

-23/3=13/6a

(-23/3)/(13/6)=a

a=-46/13

7 0

2 years ago

#10 i The table shows the admission costs (in dollars) and the average number of daily visitors at an amusement park each the pa

lions [1.4K]

The line of best fit is a straight line that can be used to predict the

average daily attendance for a given admission cost.

Correct responses:

The equation of best fit is; $\underline{ \hat Y = 1,042 - 4.9 \cdot X_i}$

The correlation coefficient is; r ≈<u> -0.969</u>

<h3>Methods by which the line of best fit is found</h3>

The given data is presented in the following tabular format;

$\begin{tabular}{|c|c|c|c|c|c|c|c|c|}Cost, (dollars), x&20&21&22&24&25&27&28&30\\Daily attendance, y&940&935&940&925&920&905&910&890\end{array}\right]$

The equation of the line of best fit is given by the regression line

equation as follows;

$\hat Y = \mathbf{b_0 + b_1 \cdot X_i}$

Where;

$\hat Y$ = Predicted value of the<em> i</em>th observation

b₀ = Estimated regression equation intercept

b₁ = The estimate of the slope regression equation

$X_i$ = The <em>i</em>th observed value

$b_1 = \mathbf{\dfrac{\sum (X - \overline X) \cdot (Y - \overline Y) }{\sum \left(X - \overline X \right)^2}}$

$\overline X$ = 24.625

$\overline Y$ = 960.625

$\mathbf{\sum(X - \overline X) \cdot (Y - \overline Y)} = -433.125$

$\mathbf{\sum(X - \overline X)^2} = 87.875$

Therefore;

$b_1 = \mathbf{\dfrac{-433.125}{87.875}} \approx -4.9289$

Therefore;

The slope given to the nearest tenth is b₁ ≈ -4.9

$b_0 = \mathbf{\dfrac{\left(\sum Y \right) \cdot \left(\sum X^2 \right) - \left(\sum X \right) \cdot \left(\sum X \cdot Y\right)} {n \cdot \left(\sum X^2\right) - \left(\sum X \right)^2}}$

By using MS Excel, we have;

n = 8

∑X = 197

∑Y = 7365

∑X² = 4939

∑Y² = 6782675

∑X·Y = 180930

(∑X)² = 38809

Therefore;

$b_0 = \dfrac{7365 \times 4939-197 \times 180930}{8 \times 4939 - 38809} \approx \mathbf{1041.9986}$

The y-intercept given to the nearest tenth is b₀ ≈ 1,042

The equation of the line of best fit is therefore;

$\underline{\hat Y = 1042 - 4.9 \cdot X_i}$

The correlation coefficient is given by the formula;

$\displaystyle r = \mathbf{\dfrac{\sum \left(X_i - \overline X) \cdot \left(Y - \overline Y \right)}{ \sqrt{\sum \left(X_i - \overline X \right)^2 \cdot \sum \left(Y_i - \overline Y \right)^2} }}$

Where;

$\sqrt{\sum \left(X - \overline X \right)^2 \times \sum \left(Y - \overline Y \right)^2} = \mathbf{446.8121}$

$\sum \left(X_i - \overline X \right) \times \left(Y - \overline Y\right) = \mathbf{-433.125}$

Which gives;

$r = \dfrac{-433.125}{446.8121} \approx \mathbf{-0.969367213}$

The correlation coefficient given to the nearest thousandth is therefore;

<u>Correlation coefficient, r ≈ -0.969</u>

Learn more about regression analysis here:

brainly.com/question/14279500

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2 years ago

A coin collector has $45 in just dimes and quarters in a piggy bank he counted all the coins and there are 240 total how many ea

Whitepunk [10]

Answer:

The number of <u>dimes are 100</u> and number of <u>quarters are 140.</u>

Step-by-step explanation:

Let the number of dimes be 'd' and quarters be 'q'.

Given:

The sum of amount is $45.

The total number of coins are 240.

1 dime = $0.10

∴ 'd' dimes = $\$0.10d$

1 quarter = $0.25

∴ 'q' quarters = $\$0.25q$

Now, as per question:

$d+m=240-----1\\0.1d+0.25q=45---2$

Multiplying equation (1) by -0.1 and adding the result to equation (2), we get:

$-0.1d-0.1q=240\times -0.1\\-0.1d-0.1q=-24\\0.1d+0.25q=45\\-----------\\0.15q=21\\q=\frac{21}{0.15}=140\\\\d=240-q=240-140=100$

Therefore, the number of dimes are 100 and number of quarters are 140.

7 0

2 years ago

a farmers packs 46 apples into trays for market.Each tray holds 6 apples.how many apples are in partially filled tray

denis23 [38]

$46 - 6 - 6 - 6 - 6 - 6 - 6-6=46-(7)(6)=46-42 = \boxed {4}$

4 0

2 years ago

Make v the subject of the formula

EleoNora [17]

$T =\dfrac 5{V+1}\\\\\\\implies VT+T = 5\\\\\implies VT = 5-T\\\\\implies V =\dfrac{5-T}T$

7 0

2 years ago

Read 2 more answers