SOLUTION: A certain 18 hole golf course has par-3 par-4 and par-5 hole and there are twice as many par-4 holes as there are par-5. How many holes of each type are there if a golfer has par o

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A certain 18 hole golf course has par-3 par-4 and par-5 hole and there are twice as many par-4 holes as there are par-5. How many holes of each type are there if a golfer has par o      Log On


   



Question 126566: A certain 18 hole golf course has par-3 par-4 and par-5 hole and there are twice as many par-4 holes as there are par-5. How many holes of each type are there if a golfer has par on every hle for a score of 70?
Answer by marcsam823(57) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = number of par-3 holes
Let y = number of par-4 holes
Let z = number of par-5 holes
Let x+%2B+y+%2B+z+=+18 (total number of holes on the course)
Let 3x = total number of strokes for par-3 holes
Let 4y = total number of strokes for par-4 holes
Let 5z = total number of strokes for par-5 holes
Let 3x+%2B+4y+%2B+5z+=+70 (total strokes to par the course)
Let y+=+2z (number of par-4 holes = twice the number of par-5 holes)

1. We'll start by reducing the number of variables from 3 to 2
Equation 1: x+%2B+y+%2B+z+=+18
Equation 2: 3x+%2B+4y+%2B+5z+=+70
We know that y+=+2z (from above) so let's substitute for y:
Equation 1:
x+%2B+2z+%2B+z+=+18
x+%2B+3z+=+18
Equation 2:
3x+%2B+4%282z%29+%2B+5z+=+70
3x+%2B+8z+%2B+5z+=+70
3x+%2B+13z+=+70
Now we have two equations with 2 variables each:
Equation 1 is now: x+%2B+3z+=+18
and
Equation 2 is now: 3x+%2B+13z+=+70
We can solve for z by eliminating the x variable:
Multiply both sides of Equation 1 by -3:
-3%28x+%2B+3z%29+=+-3%2818%29
-3x+-9z+=+-54
Add this to Equation 2 and solve for z:
3x+%2B+13z+=+70
+ -3x+-9z+=+-54
4z+=+16
z+=+4
Solve for x and y:
We know that y = 2z
y+=+2%284%29
y+=+8
We also know that x + y + z = 18
x+%2B+8+%2B+4+=+18
x+%2B+12+=+18
x+=+6
The golf course has 6 par-3 holes, 8 par-4 holes and 4 par-5 holes
Check:
Let's test these results with the original equation 2:
3x+%2B+4y+%2B+5z+=+70
3%286%29+%2B+4%288%29+%2B+5%284%29=+70
18+%2B+32+%2B+20+=+70
70+=+70
This checks. Our answers are correct.
18 + 32 + 20 = 70