The ratio in Mrs. Jones class was 10 boys to 13 girls. If the school has 700 students, how many boys attend the school?

If f(x) = x2 + 7, what is the value of f(3)?

Mazyrski [523]

Plug in 3 for f(x)
f(3)=(3)²+7
f(3)=9+7
f(3)=16
Hoped this helped!

3 0

3 years ago

Tain has a great literary tradition that spans centuries. One might assume, then, that Britons read more than citizens of other

tresset_1 [31]

Answer:

Null hypothesis: $p_{1} \leq p_{2}$

Alternative hypothesis: $p_{1} > p_{2}$

$z=3.02$

$p_v =P(Z>3.02)=0.00127$

The p value is a very low value and using any significance level for example $\alpha=0.05, 0,1,0.15$ always $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, and we can say the the proportion of Canadians is not significantly higher than the porportions of readers at Britons.

Step-by-step explanation:

1) Data given and notation

$X_{1}=0.86*1004$ represent the number of Canadians randomly sampled by Gallup that read at least one book in the past year

$X_{2}=0.81*1009$ represent the number of Britons randomly sampled that read at least one book in the past year

$n_{1}=1004$ sample of Gallup selected

$n_{2}=1009$ sample of Britons selected

$p_{1}=0.86$ represent the proportion of Canadians randomly sampled by Gallup that read at least one book in the past year

$p_{2}=0.81$ represent the proportion of Britons randomly sampled that read at least one book in the past year

z would represent the statistic (variable of interest)

$p_v$ represent the value for the test (variable of interest)

2) Concepts and formulas to use

We need to conduct a hypothesis in order to check if the proportion for men with red/green color blindness is a higher than the rate for women , the system of hypothesis would be:

Null hypothesis: $p_{1} \leq p_{2}$

Alternative hypothesis: $p_{1} > p_{2}$

We need to apply a z test to compare proportions, and the statistic is given by:

$z=\frac{p_{1}-p_{2}}{\sqrt{\hat p (1-\hat p)(\frac{1}{n_{1}}+\frac{1}{n_{2}})}}$ (1)

Where $\hat p=\frac{X_{1}+X_{2}}{n_{1}+n_{2}}=\frac{0.81+0.86}{2}=0.835$

3) Calculate the statistic

Replacing in formula (1) the values obtained we got this:

$z=\frac{0.86-0.81}{\sqrt{0.835(1-0.835)(\frac{1}{1004}+\frac{1}{1009})}}=3.02$

4) Statistical decision

For this case we don't have a significance level provided $\alpha$ , but we can calculate the p value for this test.

Since is a one side test the p value would be:

$p_v =P(Z>3.02)=0.00127$

So the p value is a very low value and using any significance level for example $\alpha=0.05, 0,1,0.15$ always $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, and we can say the the proportion of Canadians is not significantly higher than the porportions of readers at Britons.

5 0

3 years ago

A pyrotechnician plans for two fireworks to explode together at the same height in the air. They travel at speeds shown below. F

Anastasy [175]

Thank you for posting your question here at brainly. I hope the answer will help you. Feel free to ask more questions.
By the time firework a has been launched, firework b has already been launched for 0.25 seconds, so if we treat the two as equations, then

a = 220 (t)
b = 220 (t) + 220 (.25)

And we want to know when these two equal eachother, as that's they will both detonate.

220t = 200 t + 200 (.25)
20t = 50
t = 2.5

7 0

3 years ago

Help me plz Write a phrase as an algebraic expression when n = the number. (a number minus 4)

Blizzard [7]

Answer:

n-4

Step-by-step explanation:

n= the number

a number minus 4

n-4

5 0

3 years ago

Read 2 more answers

What is the equation of the parabola, in vertex form, with focus at (1, -4) and directrix x= 3?

Nezavi [6.7K]

Answer:

D. (y +4)² = -4(x -2)

Step-by-step explanation:

The directrix is a vertical line, and the focus is to the left of it. The parabola will open to the left.

The vertex is halfway between the focus and directrix, so is located on the same horizontal line as the focus, at ...

x = (1 +3)/2 = 2

The focus to vertex distance is the difference in x-coordinates: 1 -2 = -1. This is the value of p in the form ...

(y -k)² = 4p(x -h) . . . . . . . parabola with vertex (h, k)

The equation is ...

(y +4)² = -4(x -2)

_____

Additional comment

Once you determine that the directrix is a vertical line, you know the equation will have a y² term. The only answer choice that has that is D.

5 0

3 years ago