Problema Solution
Electric light bulbs can be packed in boxes of 16 to 24. How can 232 light bulbs be backed into full boxes only?
Answer provided by our tutors
let
x = the number of 16 bulb boxes
y = the number of 24 bulb boxes
the bulbs from x + the bulbs from y = total number of bulbs
16*x + 24*y = 232 divide both sides by 8
2*x + 3*y = 29
since y >=0 we have 2*x = 29 - 3*y <=29 that is x<=29/2
x < = 14
lets also notice that x is not divisible by 3 (otherwise if x is divisible by 3 the left side of the equation 2*x + 3*y = 29 will be divisible by 3 while the right side 29 is not divisible by 3)
If x = 1 then y = (29 - 2)/3 = 9 thus one solution is x=1, y=9
If x = 2 then y = (29 - 4)/3 is not integer thus is not a solution
If x = 4 then y = (29 - 8)/3 = 7 thus one solution is x=4, y=7
If x = 5 then y = (29 - 10)/3 is not integer thus is not a solution
If x = 7 then y = (29 - 14)/3 = 5 thus one solution is x=7, y=5
If x = 8 then y = (29 - 16)/3 is not integer thus is not a solution
If x = 10 then y = (29 - 20)/3 = 3 thus one solution is x=10, y=3
If x = 11 then y = (29 - 22)/3 is not integer thus is not a solution
If x = 13 then y = (29 - 26)/3 = 1 thus one solution is x=13, y=1
If x = 14 then y = (29 - 28)/3 is not integer thus is not a solution
232 bulbs can be packed in to full boxes in the following 5 ways:
1 box of 16 bulbs & 9 boxes of 24 bulbs
4 boxes of 16 bulbs & 7 boxes of 24 bulbs
7 boxes of 16 bulbs & 5 boxes of 24 bulbs
10 boxes of 16 bulbs & 3 boxes of 24 bulbs
13 boxes of 16 bulbs & 1 box of 24 bulbs