Viral Maths Problem Confusing Students & Parents

There are 73 red, blue and green marbles in a jar. There are twice as many red marbles as blue marbles. There are 19 more marbles than green marbles. 

How many green marbles are there?

Check if you are correct! 

Solution of Viral Maths Problem Confusing Students & Parents

What was the problem?

Using Algebra : 

Let r,b and g be the numbers of red, blue and green marbles in the jar.

There are 73 red, blue and green marbles in a jar.

So r + b + g = 73    .....(1)

There are twice as many red marbles as blue marbles.

r = 2b                  ......(2)

There are 19 more blue marbles than green marbles. 

b = g + 19            

g = b - 19            ......(3)

Putting (2) and (3) in (1), gives

2b + b + b - 19 = 73

4b = 92

b = 23

Putting b = 23 in (3) gives,

g = 23 - 19 = 4

Putting  b = 23 in (2), gives 

r = 2x23 = 46

So there are 46 red,23 blue and 4 green marbles in the jar.

Without Algebra :

In the case, we need to try trail and error method.

If g = 1, then b = 20 and r = 2(20) = 40 giving total 40 + 20 + 1 = 61.

If g = 2, then b = 21 and r = 2(21) = 42 giving total 42 + 21 + 2 = 65.

If g = 3, then b = 22 and r = 2(22) = 44 giving total 44 + 22 + 3 = 69.

Total is increasing at the rate of 4. So finally,

If g = 4, then b = 23 and r = 2(23) = 46 giving total 46 + 23 + 4 = 73.


So there are 46 red,23 blue and 4 green marbles in the jar.