https://docs.google.com/spreadsheets/d/1y3LRrlEQwOnCwC-3IOuJ3QTjFRY_8P4IbRoIyHqYZEI/template/preview

^^^^^^^^^^THIS LINK ABOVE CAN HELP / ITS A GOOGLE SHEET

http://www.mathandstatistics.com/learn-stats/confidence-intervals/confidence-intervals-for-means

the answer is in a tri- linear , using DECIMALS

this is what i got the last time:

Explanation:

percentage of females with c grade, p= ?255?? *100 = 20%

standard deviation =?Np(1?p)??? = ?250.2(1?0.2)??? = 0.08 or 8%

for 98% z score = 2.326

hence range = ( 20% + 2.326 * 8% , 20% + 2.326 * 8% )

= (1.392% , 38.608%)

or ( 0.01392 , 0.386 )

or 0.01392

AS YOU CAN SEE , its only partially correct .

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