# Can anyone help me with statistics? Question: Following is the distribution of marks obtained by 5

Can anyone help me with statistics?
Question: Following is the distribution of marks obtained by 500 candidates in the statistics paper of a civil services examination:
+ marks more than: 0 10 20 30 40 50
+ number of candidates: 500 460 400 200 100 30
Calculate the lower quartile marks. If $70\mathrm{%}$ of the candidates pass in the paper, find the minimum marks obtained by a passing candidate.
In the above problem, I am able to find the first part to calculate lower quartile marks but not able to find the second section.
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Makayla Santiago
Write out the cumulative distribution function $P\left(N\le m\right)$ for number of candidates N and marks m, by subtracting the numbers given from 500 and dividing by 500. You can compute what is required by simple interpolation.
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Colonninisxi
70% of 500 is 350. So the top 350 candidates passed the paper.
If the passing grade were 30 or more, this wouldn't be possible, since then only 200 candidates could have passed, at most. If the passing grade were 20 or less, it wouldn't be possible since then at least 400 students would have passed. So the passing grade is somewhere between 21 and 29 inclusive. However, it's impossible to know exactly what it is. Maybe by "the minimum" marks, they mean 21, the lowest the passing grade could possibly be?