Question
An exam worth 145
points contains 50
questions. Some of the
questions are worth two
points and some are worth
five points. How many two-
point questions are on the
test? How many five-point
questions are on the test?
Write a linear system of
equations that can be used
to solve this problem.
points contains 50
questions. Some of the
questions are worth two
points and some are worth
five points. How many two-
point questions are on the
test? How many five-point
questions are on the test?
Write a linear system of
equations that can be used
to solve this problem.
Answers
number of 2 pointers --- x
number of 3 pointers ---- y
x + y = 50 or y = 50-x
2x + 3y = 145
use substitution:
2x + 3y = 145
2x + 3(50-x) = 145
2x + 150 - 3x = 145
-x = -5
x = 5
so 5 two-pointers and 45 three-pointers
check:
5+45 = 50, the count checks
2(5) + 3(45) = 10 + 135 = 145 , the total value checks
All is good!
number of 3 pointers ---- y
x + y = 50 or y = 50-x
2x + 3y = 145
use substitution:
2x + 3y = 145
2x + 3(50-x) = 145
2x + 150 - 3x = 145
-x = -5
x = 5
so 5 two-pointers and 45 three-pointers
check:
5+45 = 50, the count checks
2(5) + 3(45) = 10 + 135 = 145 , the total value checks
All is good!
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