Question

Jenny must sit four papers for an exam. The mean of the first three papers Jenny has sat is 72%.
(a)If she wants to get an overall mean of at least 75%,what is the lowest mark she can get in her fourth paper?
(b) What is the highest possible mean she can get over all four papers?

Answer 1

p1 = paper 1

p2 = paper 2

p3 = paper 3

p4 = paper 4


( a )

The mean of the first three papers Jenny has sat is 72%.

( p1 + p2 + p3 ) / 3 = 72 % Multiply both sides by 3

p1 + p2 + p3 = 72 % * 3 =

p1 + p2 + p3 = 216 %


After 4 papres mean is :

( p1 + p2 + p3 + p4 ) / 4

If she wants to get an overall mean 75% then :

( p1 + p2 + p3 + p4 ) / 4 = 75 % Multiply both sides by 4

( p1 + p2 + p3 ) + p4 = 75 % * 4

216 % + p4 = 300 % Subtract 216 % to both sides

216 % + p4 - 216 % = 300 % - 216 %

p4 = 84 %


( b )

Maximum marks in fourth paper is 100 %.

If p4 = 100 % then :

( p1 + p2 + p3 + p4 ) / 4 =

( p1 + p2 + p3 + 100 % ) / 4 =

( 216 % + 100 % ) / 4 =

316 % / 4 = 79 %

Answer 2

thanks mush