Shobha’s Mathematics Test had 75 problems i.e., 10 arithmetic, 30 algebra and 35 geometry problems. Although she answered 70% of the arithmetic, 40% of the algebra and 60% of the geometry problems correctly, she did not pass the test because she got less than 60% of the problems right. How many more questions she would have needed to answer correctly to earn a 60% passing grade?
Answer
Answer (as printed):
Explanation
Number of questions attempted correctly $=(70\%$ of $10+40\%$ of $30+60\%$ of $35)=(7+12+21)=40$. Questions to be answered correctly for $60\%$ grade $=60\%$ of $75=45$. Required number of questions $=(45-40)=5$.
Explanation as extracted from the printed page; notation may be imperfect.