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butalik [34]
3 years ago
9

Find the value of a and of b for which(a) the solution of x2 + ax < b is-2<x < 4​

Mathematics
1 answer:
KengaRu [80]3 years ago
3 0

Answer: a = -2

b = 8

Step-by-step explanation:

Given :

x^{2} +ax

re - writing the equation , we have

x^{2} +ax-b

we need to find the value of a and b for which -2<x < 4 , this means that the roots of the quadratic equation are -2<x < 4.

The formula for finding the quadratic equation when the roots are known is :

x^{2} - sum of roots(x) + product of root = 0

sum of roots = -2 + 4 = 2

product of roots = -2 x 4 = -8

substituting into the formula , we have:

x^{2} -2x-8=0 , which could be written in inequality form as

x^{2} -2x-8

comparing with x^{2} +ax-b , it means that :

a = -2

b = 8

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Answer:

We conclude that seniors skip more than 2% of their classes at 0.01 level of significance.

Step-by-step explanation:

We are given that a professor wishes to discover if seniors skip more classes than freshmen. Suppose he knows that freshmen skip 2% of their classes.

He randomly samples a group of seniors and out of 2521 classes, the group skipped 77.

<u><em /></u>

<u><em>Let p = percentage of seniors who skip their classes.</em></u>

So, Null Hypothesis, H_0 : p \leq 2%   {means that seniors skip less than or equal to 2% of their classes}

Alternate Hypothesis, H_A : p > 2%   {means that seniors skip more than 2% of their classes}

The test statistics that will be used here is <u>One-sample z proportion</u> <u>statistics</u>;

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where, \hat p = sample proportion of seniors who skipped their classes = \frac{77}{2521}

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So, <u><em>test statistics</em></u>  =  \frac{\frac{77}{2521} -0.02}{{\sqrt{\frac{\frac{77}{2521}(1-\frac{77}{2521})}{2521} } } } }

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The value of the test statistics is 3.08.

Now at 0.01 significance level, <u>the z table gives critical value of 2.3263 for right-tailed test</u>. Since our test statistics is more than the critical value of z as 2.3263 < 3.08, so we have sufficient evidence to reject our null hypothesis as it will fall in the rejection region due to which <u>we reject our null hypothesis</u>.

Therefore, we conclude that seniors skip more than 2% of their classes.

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