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Paul has been studying for his exams. For every 3 hours he spends studying Biology, he spends 2 hours studying Chemistry.
He did not go to class and spent the entire day in the library. He only got 4 hours of sleep.
The next day, he planned to spend the same total amount of time studying, but he realized he needed to finish his Biology lab report, which takes an extra 30% of his Biology study time.
How many more hours did Paul spend studying Biology than Chemistry?
Answer choices:
A) 1 hour and 15 minutes
B) 2 hours and 20 minutes
C) 5 hours
D) 3 hours and 36 minutes
E) 1 hour and 45 minutes
Solution
Let Biology = 3x
Let Chemistry = 2x
Total study time = 24 hours − 4 hours sleep = 20 hours
3x + 2x = 20
5x = 20
x = 4 hours
So originally:
• Biology = 3(4) = 12 hours
• Chemistry = 2(4) = 8 hours
Biology increases by 30% due to the lab report:
12 × 1.3 = 15.6 hours
Convert decimal to minutes:
0.6 × 60 = 36 minutes
Difference between Biology and Chemistry:
15.6 − 12 = 3.6 hours
Final Answer:
✅ 3 hours and 36 minutes (D)
