Help with a word problem, deals with inequalities?

Question

The Jefferson College basketball team has two guards who are 6'3 tall and two forwards who are 6'7 tall. How tall must their center be to ensure the "starting five" will have an average height of at least 6'6?

So i tried adding all this up with an x for the missing center and dividing by 5 which equals to 6'6 (THis is how i set up my equation) but i end up getting some weird answer. Please help thanks :)

Answer 1

It would be easier to convert all the heights to inches.

6'3" = 75"

6'7" = 79"

6'6" = 78"

Equation:

(75 + 75 + 79 + 79 + x)/5 ≥ 78

(308 + x)/5 ≥ 78

Cross multiply:

78 × 5 ≥ 308 + x

390 ≥ 308 + x

82 ≥ x

Convert 82" back to feet.

6'10" ≥ x

Answer 2

First of all you can drop the 6' because that has to be a given.

(3+3+7+7+X)/5=>6

3+3+7+7+X => 30

20+X =>30

X => 30-20

X => 10

So the answer is 6' 10"

Answer 3

Well first convert the lenghts into total inches.

First 6'3 = (6*12)+3=75, then

6'7= (6*12)+7= 79 and 6'6 = (6*12)+6=78.

So, letting x be center's length, then

((2*75)+(2*79)+x)/5 => 78, or

x=> (5*78)-(2*75)-(2*79), or

x=>82 inches, or

x=>6'10.

But check calculations.