That Maths Question

Last week, my aunt asked me a Maths question that she chanced upon in a magazine.

Below is the question:


The above is just an illustration.

How long will both of them take to paint 1 house together?

I know the answer is NOT 6, neither is it 3. I also know the answer should be between 2 to 3.

I used the trial-and-error method and found out that the answer is between 2.5 to 2.75 hours.

After much discussion, we settled for that answer.

But few hours later, I realised that little had I solved the mystery (get the answer) in the steps of the trial-and-error method.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

The answer is 2.67 hours.



This is ridiculous. No need for trial-and-error. No need for algebra. It is that simple. I think a primary school kid can solve this within seconds.

It will be complicated when "Person A takes 0.5 hour after every 2 hours" is added to the question. Nah, I am not bothered to answer this question now.


Just a random thought, higher education has taught us so many things that we do not see simple things as just that simple anymore.
Or may be it is just me who did not see it when it is so easy.