In a given course a student receives preliminary examination grades of 81, 85, and 95. the final examination is weighed for one-third and the average of the preliminary grades is weighed as 2/3 of the final grade. what should the final examination grade be for a semester average of 90?

The average of the 3 grades = (81+85+95) /3 =87

This counts as 2/3 of the final grade:

87 * 2/3 = 58 points

For a grade of 90, they still need 90 -58 = 32 points

Let x = final exam score

The final exam is worth 1/3, so we get:

1/3x = 32

To get x, multiply both sides by 3:

x = 32 *3

x = 96

They need a 96 on the final exam.

step-by-step explanation:

given that there are two triangles j'k'l' and jkl>

the former is got by dilating the second one.

when drawn on a grid, (graph paper) coordinates of vertices of first triangle is

(6,12)j, (9,6)k and (12,9)l

side jk has length = distance between j and k

=

side j'k'=distance between j' and k'

=

ie j'k'l' has sides 1/3 of that of corresponding sides of jkl.

hence scale factor of 1/3 is used to get j'k'l'from jkl

25% is the answer