More Word Problem - 2 scenerios

Question :

Mr Tan bought a bag of sweets for his class.  If he gives 13 sweets to each of his pupils equally, he has 4 sweets left.  If he gives 8 sweets to each of his pupils equally, he has 214 sweets left. How many pupils are there in his class?

Method 1 :

Differences in sweets to each pupils        13 - 8 = 5
Difference in total of sweets left              214 - 4 = 210

Nos. of pupils  =  Difference in total of sweets left / Differences in sweets to each pupils
                      =  210 / 5 = 42


                                                                                    Ans : 42 pupils


Methods 2 :

Let the Nos. of pupils in the class be 1 unit
Total sweets = sweet gave + sweets left
        13 units + 4  =  8 units + 214
        13 units - 8 unit 214 - 4
                       5 units210
                       1 unit 210 / 5 = 42


                                                                                    Ans : 42 pupils

Remarks :

Many students approach to solve this type of problem with guess & check method.  Although it is one of the approve ways of solving the problem, personally, I feel it take more time with guess & check method.  With the above 2 methods, it will give student more time to check their test papers by solving the problem faster.  It is also my advice to student that whenever problem need to be solve by guess and check.  They should reserve it to the last and spend their time firstly on question that they can solve quickly.