SOLUTION: Hi! if x=53.33 and it represents 45% of a total mark of a course, and Y (final exam) is 55% of it, how much should Y be if the total needs to be 70% or more? I am trying to calc

Algebra ->  Equations -> SOLUTION: Hi! if x=53.33 and it represents 45% of a total mark of a course, and Y (final exam) is 55% of it, how much should Y be if the total needs to be 70% or more? I am trying to calc      Log On


   

Question 1077447: Hi!
if x=53.33 and it represents 45% of a total mark of a course, and Y (final exam) is 55% of it, how much should Y be if the total needs to be 70% or more?
I am trying to calculate the needed mark for a course final exam.
Thank you!!!
Answer by srinivas.g(540) About Me  (Show Source):
You can put this solution on YOUR website!
let total marks of the course be t and x represents marks in mid exam and y represents marks in final exam
Total marks of the course = 45% of mid exam + 55 % of final exam
t = 45 % of t + 55 % of y
marks in mid exam = x
x= 53.33 which is 45 % total marks of the course
that means 53.33 = 45 % of t
+53.33+=+%2845%2F100%29%2At
+53.33+%2A100+=+45t
5333+=+45t
+45t=5333
t=+5333%2F45
t+=+118.51
Therefore, total marks of the course = 118.51
total marks should be 70 % or more
Total marks required = 70 % of 118.51
= 0.7*118.51
=82.96
hence 82.96 = 53.33+ 55 % of y
82.96 -53.33 = 55 % of y
29.63 = 55 % of y
29.63+=+%2855%2F100%29%2Ay
+29.63%2A100+=55y
+y+=+2963%2F55
+53.87
Hence y should be more than or equals to 53.87