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Sohana's mathematics test had 75 problems i.e. 10 arithmetic, 30 algebra and 35 geometry problems each carrying I mark She answered 70% of the arithmetic, 40% of the algebra and 60% of the geometry problems correctly. She did not pass the test as she got less than 60% marks. How many more questions she would have needed to answer correctly to earn a 60% passing grade?
Total no. of problems is 75
70% of 10 are arithmetic =10070×10=7 right
40% of 30 are algebra =10040×30=12 right
60% of 35 are geometry =10060×35=21 right
Total of right problems =7+12+21=40
% of right problems =7540×100=53.3%
To get 60% she needs 10060×75=45 right problems
So she needs 45−40=5 more problems right to get 60%.
