Question

PLEASE HELP ASAP! THANKS!

1) How much water should we add to 35 kg of sugar syrup to change its concentration from 30% to 25%?

2) John can create 3 apps in 6 weeks while Ben can do the same job in 2 weeks. How many weeks would it take them to create 10 apps together?

3)If 120% of a is equal to 80% of b, then what is the value of a+b? In terms of a? In terms of b?

Answer 1

See below

Explanation:

1) Let us tabulate and see.

Sugar content Water Total weight

I syrup 0.3(35) = 10.5 35-10.5 = 24.5 35

II syrup 0 x x

total 10.5 24.5+x 35+x

concentration in new syrup=
`(10.5)/(35+X) =0.25\\10.5 = 8.75+0.25x\\1.75 = 0.25x\\x =7 kg`

7kg of water should be added.

2) John can do 3/6 apps in one week while Ben can do 2/6 apps in one week.

Together they can do 5/6 apps per week.

Hence to do 10 apps they require 12 weeks.

3) 120% of a = 80% of b

i.e. 1.2a = 0.8b

Or 3a=2b

Or a:b = 2:3

By commendo and dividendo we get

a:a+b= 2:5

Or a+b = 5a/2 ... i

Next is

a+b:b =5:3

Or a+b= 5b/3