Every confidence interval has associated z value. As confidence interval increases so do the z value associated with it.
The confidence interval can be calculated using following formula:

Where

is the mean value, z is the associated z value, s is the standard deviation and n is the number of samples.
We know that standard deviation is simply a square root of variance:

The confidence interval of 95% has associated z value of <span>1.960.
</span>Now we can calculate the confidence interval for our income:
<span>If you have a high confidence level, the chance of rejecting the null hypothesis is rare.
If you have a low confidence level, the chance of of rejecting the null hypothesis is nonexistent.
If you have a low confidence level, the chance of of rejecting the null hypothesis is rare.
If you have a high confidence level, the chance of of rejecting the null hypothesis is high.</span>
Answer:
a = 1 b = -1.
Step-by-step explanation:
Suppose the quotient when you divide x^4+x^3+ax+b by x^2 + 1 is
x^2 + ax + b then expanding we have:
(x^2 + 1)(x^2 + ax + b)
= x^4 + ax^3 + bx^2 + x^2 + ax + b
= x^4 + ax^3 + (b + 1)x^2 + ax + b Comparing this with the original expression:
x^4 + x^3 + 0 x^2 + ax + b Comparing coefficients:
a = 1 and b+ 1 = 0 so b = -1.