P6 Math: Teachers and Pupils

20% of the people in a school hall are teachers and the rest are pupils. 75% of the pupils are boys and there are 72 more boys than girls. How many boys must leave the hall so that 20% of the people in the hall are boys ?

P6 Math: Red and White Roses Ratio

There are 60 roses in a box. 30% of the roses are red roses while the rest are white roses. How many of red roses must be added so that the number of red roses will become 40%?

P6 Math : Painting Job

It is quite common question asked in the Speed chapter. A bit twist, rather than DISTANCE, now it is asking JOB.

Example:

John, Mark, and Shaun were hired to paint a house.

Together, they can finish the job in one hour.

John and Mark can finish the job in 1 hour 12 minutes.

Mark and Shaun can finish the job in 1 hour 30 minutes.

How long in minutes will Mark take to finish the same job by himself ?