Data Interpretation - Table Charts - Discussion

I didn't get ths caclculation in any way help me in a siple way.

Here they have mentioned that students getting at least 60% marks in chemistry. My question is why can't we take students who scored 40% and above then the calculation will go this way.

Students who scored 30% and above=21.

Students who scored 40% and above=4.

Total = 21+4 = 25.

Similarly for students who scored aggregate marks.

Why it is taken from 20% and above it can go lower.

Or it could be taken directly from 40% and above that means only 7 is taken into consideration.

At-least consider minimum to minimum so,

60% of chem=50*0.6=30 (so 21).

similarly 40% of agg=50*0.4=20 (so 73).

Finally,

(21/73) *100=28.77==29%.

@Pradeepika.

30 and above i.e. 40 is above 30 only so no need to include 40 and above as it is already in 30 and above.

Fast calculation using fraction:

(21/73)*100~(20/70)*100 = (2/7)*100 = (2*1/7)*100 = (2*14.28)*100 = 28.56%.

So answer approximately 29%.

Why we are not take 50*0.6 equal to 40?

30 and above marks students comes under 60% = 27 students.
40 and above marks students comes under 20% = 73 students.

Here they are asking " The percentage of number of students getting at least 60% marks in Chemistry over those getting at least 40% marks in aggregate ".

Therefore we calculate 27/73 X 100.

By solving, we will get the answer.

Actually (60/100)*50=30...so yu go 30and above in chemistry. now you get 21, keep it safe...then you must go to aggregate atleast40% (40/100)*50=20.

so you go 20and above in aggregate, now, you get 73.

Then you find the required percentage ..(21/73)*100=28.77% ~=29%.

Please, anyone explain this to me.

60% of chemistry means (60/100 * 50) =30.
So we have to take 30 above in chemistry i.e =21.
40 % of aggregate means (40/100 *50) = 20.
So we have to take 20 above in aggraget i.e = 73
Now we have to find a percentage so (21/73 *100).
Hence we get (28.77).