On a test consisting of 250 questions, Jassi answered 40% of the first 125 questions correctly. What percent of the other 125 questions does she need to answer correctly for her grade on the entire exam to be 60% ?

Answer: Option C

Number of questions answered correctly = 40% of 125 = 50
For 60% grade, number of questions to be answered correctly = 60% of 250 = 150
Remaining number of questions to be answered correctly
= 150 - 50
= 100
∴ Required percentage
$$\begin{array}{rl}& =\left(\frac{100}{125}\times 100\right)\%\\ & =80\%\end{array}$$