A test was marked out of 80. a boy scored 60% of the marks on the test. how many did he score?

A dairy sells $3 and $5 ice creams. In one day they sell 50 ice creams earning a total of $180. How many of each type of ice cre

murzikaleks [220]

We are going to make simultaneous equations.
x will be our $3 ice cream and y will be our $5 ice cream

Equation1 ---- x + y = 50 (the sum of all the ice creams they sell)
Equation 2 ---- 3x + 5y = 180 Sum of all the $3 and $5 ice creams is $180
Since we can't solve for both variables we will put one of the variables in terms of the other.
Take x+y=50 and subtract y from both sides. (I could have done subtracted x - it did not matter). Now we have x= ₋ y +50 (negative y +50)
Now I am going to take equation 2 and replace the x with -y +50

3 (-y +50) + 5y = 180
Now I will use the distributive law on the 3 and what's in the parentheses:
-3y + 150 + 5y = 180
Now I will combine like terms (the -3y and the 5y)
2y + 150 = 180
Now subtract 150 from both sides of the equation
2y = 30
Divide both sides by 2
and get y= 15 They sold 15 ice creams that cost $5 each
Since equation 1 is x+y=50 we can replace y with 15
x + 15 = 50 Now subtract 15 from both sides x = 35
Since x represents the $3 ice creams, they sold 35 of those.
Check:
35 X 3 = $105
15 x 5 = + <u>75
</u> $180

8 0

2 years ago

Jensen Tire & Auto is in the process of deciding whether to purchase a maintenance contract for its new computer wheel align

sasho [114]

Answer:

Step-by-step explanation:

Hello!

The given data corresponds to the variables

Y: Annual Maintenance Expense ($100s)

X: Weekly Usage (hours)

n= 10

∑X= 253; ∑X²= 7347; $\frac{}{X}$ = ∑X/n= 253/10= 25.3 Hours

∑Y= 346.50; ∑Y²= 13010.75; $\frac{}{Y}$ = ∑Y/n= 346.50/10= 34.65 $100s

∑XY= 9668.5

a)

To estimate the slope and y-intercept you have to apply the following formulas:

$b= \frac{sumXY-\frac{(sumX)(sumY)}{n} }{sumX^2-\frac{(sumX)^2}{n} } = \frac{9668.5-\frac{253*346.5}{10} }{7347-\frac{(253)^2}{10} }= 0.95$

$a= \frac{}{Y} -b\frac{}{X} = 34.65-0.95*25.3= 10.53$

^Y= a + bX

^Y= 10.53 + 0.95X

b)

H₀: β = 0

H₁: β ≠ 0

α:0.05

$F= \frac{MS_{Reg}}{MS_{Error}} ~~F_{Df_{Reg}; Df_{Error}}$

F= 47.62

p-value: 0.0001

To decide using the p-value you have to compare it against the level of significance:

If p-value ≤ α, reject the null hypothesis.

If p-value > α, do not reject the null hypothesis.

The decision is to reject the null hypothesis.

At a 5% significance level you can conclude that the average annual maintenance expense of the computer wheel alignment and balancing machine is modified when the weekly usage increases one hour.

b= 0.95 $100s/hours is the variation of the estimated average annual maintenance expense of the computer wheel alignment and balancing machine is modified when the weekly usage increases one hour.

a= 10.53 $ 100s is the value of the average annual maintenance expense of the computer wheel alignment and balancing machine when the weekly usage is zero.

c)

The value that determines the % of the variability of the dependent variable that is explained by the response variable is the coefficient of determination. You can calculate it manually using the formula:

$R^2 = \frac{b^2[sumX^2-\frac{(sumX)^2}{n} ]}{[sumY^2-\frac{(sumY)^2}{n} ]} = \frac{0.95^2[7347-\frac{(253)^2}{10} ]}{[13010.75-\frac{(346.50)^2}{10} ]} = 0.86$

This means that 86% of the variability of the annual maintenance expense of the computer wheel alignment and balancing machine is explained by the weekly usage under the estimated model ^Y= 10.53 + 0.95X

d)

Without usage, you'd expect the annual maintenance expense to be $1053

If used 100 hours weekly the expected maintenance expense will be 10.53+0.95*100= 105.53 $100s⇒ $10553

If used 1000 hours weekly the expected maintenance expense will be $96053

It is recommendable to purchase the contract only if the weekly usage of the computer is greater than 100 hours weekly.

4 0

2 years ago

Which graph represents the function of f(x) 9x^2 -36 / 3x + 6

Finger [1]

Answer:

The graph in the attached figure

Step-by-step explanation:

we have

$f(x)=\frac{9x^{2}-36}{3x+6}$

Remember that the denominator cannot be equal to zero

so

The value of x cannot be equal to x=-2

<em>Simplify the numerator</em>

$9x^{2}-36=(3x+6)(3x-6)$ ----> by difference of squares

substitute

$f(x)=\frac{(3x+6)(3x-6)}{3x+6}$

simplify

$f(x)=3x-6$

The domain is all real numbers except the value of x=-2

The y-intercept is the point (0,-6) ---> value of y when the value of x is equal to zero)

The x-intercept is the point (2,0) ---> value of x when the value of y is equal to zero)

therefore

The graph in the attached figure

7 0

3 years ago

2/5 + 1/3= in Simplest form

expeople1 [14]

Thye have to have like denominators.

So it becomes, 6/15+5/15 which is equal to 11/15

6 0

3 years ago

Read 2 more answers

PPPPPPLLLLLLEEAAASSEE HELLLPPP WIL MARK BRAINLIEST the brackets for a shelf are in the shape of a triangle. Find the angles of t

ahrayia [7]

Answer:

Step-by-step explanation:

Sum of the angles of a triangle is ALWAYS 180°.

2x+3x+5x = 180°

10x = 180°

x = 18°

2x = 36°

3x = 54°

5x = 90°

The angles are 36°, 54°, and 90°

6 0

2 years ago