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goldfiish [28.3K]
3 years ago
9

PLS HELP!!! There are 42 new houses being built in a neighborhood. Last month, 2/3 of them were sold. This month, 2/7 of the rem

aining houses were sold. How many houses are left to be sold?
Mathematics
1 answer:
Eva8 [605]3 years ago
8 0

Answer:

0.5

Step-by-step explanation:

42 divided by 2/3 = 7

7 divided by 2/7 = 0.5

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Solve for the values of x and y.
Alekssandra [29.7K]

Answer:

x = 20

y = 7.2

Step-by-step explanation:

12/x = 9/15

9x = 180

x = 20

12/x= y/12

12/20 = y/12

144 = 20y

y = 7.2

y = 20

8 0
3 years ago
The height in feet above the water of a diver can be modeled by ℎ() = −16*2 − 16 + 192, where t is the time in seconds after the
Maurinko [17]

h(t) is the height of the diver in feet above the water

Now it asks about the time at which diver reaches the water

When diver reaches the water , the height of diver from water should be zero

So we plug h(t) =0

So

-16t^2 -16 t +192 =0

divide whole equation by -16

t^2 +t -12 =0

we can now factor the quadratic equation

So we get

(t+4)(t-3) =0

plug each factor equal to zero and solve for t

t+4 =0 and t-3 =0

So t=-4 and t=3

Now time cannot be negative , So t=3

So time = 3 seconds

It takes 3 seconds for the diver to reach the water

3 0
3 years ago
What are the solutions to this system of equations?
saveliy_v [14]

Answer:

A

Step-by-step explanation:

The solution is at the points of intersections of the graphs

The graphs intersect at (- 3, 0 ) and (2, 5 )  , then

solutions are (- 3, 0 ) and (2, 5 )

4 0
2 years ago
What is the slope of (-5,-1) (5,5)? Explain.
ArbitrLikvidat [17]

Step-by-step explanation:

slope =   \frac{ - 1 - 5}{ - 5 - 5}  = \frac{ - 6}{ - 10}   = \frac{ 3}{ 5} \\

3 0
3 years ago
Read 2 more answers
a math teacher claims that she has developed a review course that increases the score of students on the math portion of a colle
madam [21]

Answer:

A.

H_0: \mu\leq514\\\\H_1: \mu>514

B. Z=2.255. P=0.01207.

C. Although it is not big difference, it is an improvement that has evidence. The scores are expected to be higher in average than without the review course.

D. P(z>0.94)=0.1736

Step-by-step explanation:

<em>A. state the null and alternative hypotheses.</em>

The null hypothesis states that the review course has no effect, so the scores are still the same. The alternative hypothesis states that the review course increase the score.

H_0: \mu\leq514\\\\H_1: \mu>514

B. test the hypothesis at the a=.10 level of confidence. is a mean math score of 520 significantly higher than 514? find the test statistic, find P-value. is the sample statistic significantly higher?

The test statistic Z can be calculated as

Z=\frac{M-\mu}{s/\sqrt{N}} =\frac{520-514}{119/\sqrt{2000}}=\frac{6}{2.661}=2.255

The P-value of z=2.255 is P=0.01207.

The P-value is smaller than the significance level, so the effect is significant. The null hypothesis is rejected.

Then we can conclude that the score of 520 is significantly higher than 514, in this case, specially because the big sample size.

C.​ do you think that a mean math score of 520 vs 514 will affect the decision of a school admissions adminstrator? in other words does the increase in the score have any practical significance?

Although it is not big difference, it is an improvement that has evidence. The scores are expected to be higher in average than without the review course.

D. test the hypothesis at the a=.10 level of confidence with n=350 students. assume that the sample mean is still 520 and the sample standard deviation is still 119. is a sample mean of 520 significantly more than 514? find test statistic, find p value, is the sample mean statisically significantly higher? what do you conclude about the impact of large samples on the p-value?

In this case, the z-value is

Z=\frac{520-514}{s/\sqrt{n}} =\frac{6}{119/\sqrt{350}} =\frac{6}{6.36} =0.94\\\\P(z>0.94)=0.1736>\alpha

In this case, the P-value is greater than the significance level, so there is no evidence that the review course is increasing the scores.

The sample size gives robustness to the results of the sample. A large sample is more representative of the population than a smaller sample. A little difference, as 520 from 514, but in a big sample leads to a more strong evidence of a change in the mean score.

Large samples give more extreme values of z, so P-values that are smaller and therefore tend to be smaller than the significance level.

8 0
3 years ago
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