Sophia washes pots in 30 minutes. Her mother takes 15 minutes to wash same amount of them. How much time will it take if they wash those dishes together?
Asked
Active
Viewed 87 times
0
-
What have you done so far to solve this? – For the love of maths Jan 03 '18 at 15:43
2 Answers
1
Sophie does $1/30$ of the dishes in $1$ minute while her mother does $1/15$. So in a minute they both together do $3/30 $ of the dishes. Thus they do all the dishes in $10$ minutes.
jonsno
- 7,521
-
Handy trick for problems like this: If 1 person can perform a task in $x$ minutes (or hours or days, etc.), and a second person can perform the same task in $y$ minutes (or hours or days, etc., assuming it's the same units as the first amount of time), then together they can perform the task in $\frac{xy}{x+y}$ minutes (or hours or days, etc.). – Grey Matters Jan 04 '18 at 02:05
0
In $10$ minutes, her mother will have washed two thirds of the dishes and Sophia will have washed one third of the dishes.
A. Goodier
- 10,964