Question #a3553

2 Answers
Oct 21, 2017

Hao should buy 55 cans of dog food to feed his dog for the next 6 weeks.

Explanation:

Ok, so if Hao's dog ate 40 cans of dog food in 31 days, then he therefore ate #40/31=1.29# cans of dog food per day.

So, there are (#6 times 7 = 42)# days in 6 weeks, so the amount of cans that Hao should buy to feed his dog for 6 weeks can be calculated by:

#1.29 times 42 = 54.18# cans, but then Hao should buy 55 cans as we cannot buy 0.18 of a can. Thus, assuming that Hao's dog eats ~1.29 cans of dog food per day, Hao should buy 55 cans of dog food to feed his dog over the next 6 weeks.

Oct 21, 2017

55 cans

Explanation:

Notice the trap! Over the next 6 #color(red)(weeks)#
The original condition is in #color(red)(days)#

Using ratio in fraction format.

Let the unknown count of cans be #x#

# ("consumption in cans")/("time in days")->40/31 =x/(6xx7)#

To get #x# on its own multiply both sides by #color(red)(42)#

#color(green)(40/31 =x/42color(white)("ddd")->color(white)("ddd") 40/31color(red)(xx42)=x/42color(red)(xx42)#

#color(white)("dddddddddd")->color(white)("ddd")color(green)((40color(red)(xx42))/31 =x xx (color(red)(42))/42)#

#color(white)("dddddddddd")->color(white)("ddddd") 1680/31=x#

For 6 weeks the consumption is exactly #color(white)("d")54 6/31 color(white)("d")"cans" #

Approximately #54.1935# cans tp 4 decimal places

Rounding this gives 55 cans: you do not purchase part of a can.