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frozen [14]
2 years ago
8

Suppose a flare is shot from the top of a 120 foot building at a speed of 160 feet per second. The equation h = ?16t + 160t + 12

0 models the h height at t seconds of the flare. How long will it take for the flare to hit the ground? (to the nearest tenth of a second)
Mathematics
1 answer:
insens350 [35]2 years ago
4 0

Answer:

The time taken for the flare to hit the ground is approximately 10.7 seconds.

Step-by-step explanation:

Given : Suppose a flare is shot from the top of a 120 foot building at a speed of 160 feet per second. The equation h =- 16t^2+ 160t + 120 models the h height at t seconds of the flare.

To find : How long will it take for the flare to hit the ground?

Solution :

The equation  h =- 16t^2+ 160t + 120 models the h height at t seconds of the flare.

The flare to hit the ground when h=0.

Substitute in the equation,

-16t^2+ 160t + 120=0

Applying quadratic formula, x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}

Where, a=-16, b=160 and c=120

x=\frac{-160\pm\sqrt{160^2-4(-16)(120)}}{2(-16)}

x=\frac{-160\pm\sqrt{33280}}{-32}

x=\frac{-160\pm 182.42}{-32}

x=\frac{-160+182.42}{-32},\frac{-160-182.42}{-32}

x=−0.70,10.70

Reject the negative value.

Therefore, the time taken for the flare to hit the ground is approximately 10.7 seconds.

You might be interested in
Suppose you are interested in the effect of skipping lectures (in days missed) on college grades. You also have ACT scores and h
DIA [1.3K]

Answer:

a) For this case the intercept of 2.52 represent a common effect of measure for any student without taking in count the other variables analyzed, and we know that if HSGPA=0, ACT= 0 and skip =0 we got colGPA=2.52

b) This value represent the effect into the ACT scores in the GPA, we know that:

\hat \beta_{ACT} = 0.015

So then for every unit increase in the ACT score we expect and increase of 0.015 in the GPA or the predicted variable

c) If we are interested in analyze if we have a significant relationship between the dependent and the independent variable we can use the following system of hypothesis:

Null Hypothesis: \beta_i = 0

Alternative hypothesis: \beta_i \neq 0

Or in other wouds we want to check if an specific slope is significant.

The significance level assumed for this case is \alpha=0.05

Th degrees of freedom for a linear regression is given by df=n-p-1 = 45-3-1 = 41, where p =3 the number of variables used to estimate the dependent variable.

In order to test the hypothesis the statistic is given by:

t=\frac{\hat \beta_i}{SE_{\beta_i}}

And replacing we got:

t = \frac{-0.5}{0.0001}=-5000

And for this case we see that if we find the p value for this case we will get a value very near to 0, so then we can conclude that this coefficient would be significant for the regression model .

Step-by-step explanation:

For this case we have the following multiple regression model calculated:

colGPA =2.52+0.38*HSGPA+0.015*ACT-0.5*skip

Part a

(a) Interpret the intercept in this model.

For this case the intercept of 2.52 represent a common effect of measure for any student without taking in count the other variables analyzed, and we know that if HSGPA=0, ACT= 0 and skip =0 we got colGPA=2.52

(b) Interpret \hat \beta_{ACT} from this model.

This value represent the effect into the ACT scores in the GPA, we know that:

\hat \beta_{ACT} = 0.015

So then for every unit increase in the ACT score we expect and increase of 0.015 in the GPA or the predicted variable

(c) What is the predicted college GPA for someone who scored a 25 on the ACT, had a 3.2 high school GPA and missed 4 lectures. Show your work.

For this case we can use the regression model and we got:

colGPA =2.52 +0.38*3.2 +0.015*25 - 0.5*4 = 26.751

(d) Is the estimate of skipping class statistically significant? How do you know? Is the estimate of skipping class economically significant? How do you know? (Hint: Suppose there are 45 lectures in a typical semester long class).

If we are interested in analyze if we have a significant relationship between the dependent and the independent variable we can use the following system of hypothesis:

Null Hypothesis: \beta_i = 0

Alternative hypothesis: \beta_i \neq 0

Or in other wouds we want to check if an specific slope is significant.

The significance level assumed for this case is \alpha=0.05

Th degrees of freedom for a linear regression is given by df=n-p-1 = 45-3-1 = 41, where p =3 the number of variables used to estimate the dependent variable.

In order to test the hypothesis the statistic is given by:

t=\frac{\hat \beta_i}{SE_{\beta_i}}

And replacing we got:

t = \frac{-0.5}{0.0001}=-5000

And for this case we see that if we find the p value for this case we will get a value very near to 0, so then we can conclude that this coefficient would be significant for the regression model .

7 0
2 years ago
Evaluate the expression a + c for a = 22 and c = 11.
bixtya [17]

Answer: 33

Step-by-step explanation: substitute a with 22 and c with 11.

22+11=33

4 0
3 years ago
Read 2 more answers
) Aubrey can walk 4 1/2 miles in 1/2 hours. Find the average speed in miles per hour.
Irina-Kira [14]
I think the answer is 5 because you add the 1/2 and the other 1/2 leave the for alone that will give you 5 Example: 1/2+1/2=1+4=5
8 0
3 years ago
The sum of three numbers in <br> g.p. is 21 and the sum of their squares is 189. find the numbers.
sashaice [31]
Let the three gp be a, ar and ar^2
a + ar + ar^2 = 21 => a(1 + r + r^2) = 21 . . . (1)
a^2 + a^2r^2 + a^2r^4 = 189 => a^2(1 + r^2 + r^4) = 189 . . . (2)
squaring (1) gives
a^2(1 + r + r^2)^2 = 441 . . . (3)
(3) ÷ (2) => (1 + r + r^2)^2 / (1 + r^2 + r^4) = 441/189 = 7/3
3(1 + r + r^2)^2 = 7(1 + r^2 + r^4)
3(r^4 + 2r^3 + 3r^2 + 2r + 1) = 7(1 + r^2 + r^4)
3r^4 + 6r^3 + 9r^2 + 6r + 3 = 7 + 7r^2 + 7r^4
4r^4 - 6r^3 - 2r^2 - 6r + 4 = 0
r = 1/2 or r = 2
From (1), a = 21/(1 + r + r^2)
When r = 2:
a = 21/(1 + 2 + 4) = 21/7 = 3
Therefore, the numbers are 3, 6 and 12.
3 0
2 years ago
the larger of two number is 15 more than three times the smaller number. If the sum of the two numbers is 63, find tge numbers.
irakobra [83]
X is the smaller number. 3x + 15 is the larger number. So x + 3x + 15 = 63. 4x + 15 = 63.
4x = 48. x = 12. (Smaller number) The larger 36 + 15 or 51.
6 0
3 years ago
Read 2 more answers
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