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

Step-by-step explanation:

Given :

re - writing the equation , we have

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 :

- 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:

, which could be written in inequality form as

comparing with , it means that :

The students scoring more than 366 will be best 80%of all applicants.

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 426

Standard Deviation, σ = 72

We are given that the distribution of score is a bell shaped distribution that is a normal distribution.

Formula:

We have to find the value of x such that the probability is 0.2

P(X < x)  

Calculation the value from standard normal z table, we have,  

Hence, the the passing score is 366 or higher. The students scoring more than 366 will be best 80%of all applicants.