Is 3 - -80 positive or negative?

PC-CSIL

pav-90 [236]

The equality used is Subtraction property of equality

Option A is correct

Step-by-step explanation:

We need to identify which option best explains or justifies Step 1.

Step 1 is: $-c = ax^2 + bx$

The given equation is: $0 = ax^2 + bx + c$

To get the equation for step 1 we need to subtract c on both sides of equation i.e using subtraction property of equality

$0-c = ax^2 + bx + c-c$

$-c = ax^2 + bx$

So, The equality used is Subtraction property of equality

Option A is correct.

Keywords: Solving Quadratic Equations

Learn more about Solving Quadratic Equations at:

#learnwithBrainly

5 0

3 years ago

We're testing the hypothesis that the average boy walks at 18 months of age (H0: p = 18). We assume that the ages at which boys

marusya05 [52]

Answer:

II. This finding is significant for a two-tailed test at .01.

III. This finding is significant for a one-tailed test at .01.

d. II and III only

Step-by-step explanation:

1) Data given and notation

$\bar X=19.2$ represent the battery life sample mean

$\sigma=2.5$ represent the population standard deviation

$n=25$ sample size

$\mu_o =18$ represent the value that we want to test

$\alpha$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

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

2) State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the mean battery life is equal to 18 or not for parta I and II:

Null hypothesis: $\mu = 18$

Alternative hypothesis: $\mu \neq 18$

And for part III we have a one tailed test with the following hypothesis:

Null hypothesis: $\mu \leq 18$

Alternative hypothesis: $\mu > 18$

Since we know the population deviation, is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

3) Calculate the statistic

We can replace in formula (1) the info given like this:

$z=\frac{19.2-18}{\frac{2.5}{\sqrt{25}}}=2.4$

4) P-value

First we need to calculate the degrees of freedom given by:

$df=n-1=25-1=24$

Since is a two tailed test for parts I and II, the p value would be:

$p_v =2*P(t_{(24)}>2.4)=0.0245$

And for part III since we have a one right tailed test the p value is:

$p_v =P(t_{(24)}>2.4)=0.0122$

5) Conclusion

I. This finding is significant for a two-tailed test at .05.

Since the $p_v$ . We reject the null hypothesis so we don't have a significant result. FALSE

II. This finding is significant for a two-tailed test at .01.

Since the $p_v >\alpha$ . We FAIL to reject the null hypothesis so we have a significant result. TRUE.

III. This finding is significant for a one-tailed test at .01.

Since the $p_v >\alpha$ . We FAIL to reject the null hypothesis so we have a significant result. TRUE.

So then the correct options is:

d. II and III only

6 0

3 years ago

Cassie rolls a fair number cube with 6 faces labeled 1 through 6 she rolls the number cube 300 times which results is most likel

ollegr [7]

It depend upon what you roll it could be 6 because there are 6 faces are the dice

3 0

2 years ago

Amy ate 2 1/2 cookies after lunch ,and 1 2/5 cookies after dinner.How many cookies did she eat altogether

Mrac [35]

2 1/2 + 1 2/5 = 3 9/10...Please give brainliest....

3 0

3 years ago

Read 2 more answers

Solve the problem.

In-s [12.5K]

Answer:

16.9%

Step-by-step explanation:

Let's find the answer by using the following formula:

final people=(initial people)+((initial people)*(percent increase)) which can be written as:

percent increase=((final people)-(initial people))/(initial people) so:

percent increase=(83-71)/71=0.169=16.9%

In conclusion, the percent increase is 16.9%.

4 0

3 years ago