Mathematical Reasoning
Alice and Sophie were both tasked to type a document with the same number of words. Alice typed 40 words per …
Question 1 · Multiple choice
Question
Alice and Sophie were both tasked to type a document with the same number of words. Alice typed 40 words per minute on average. After Sophie typed 80 words, Alice started typing. After 16 minutes, they both finished the task simultaneously. How many words did Sophie type per minute on average?
Options
- A.30 words per minute
- B.32 words per minute
- C.33 words per minute
- D.35 words per minute
- E.40 words per minute
Correct answer
Explanation
Step 1: Find the total number of words in the document
After Alice starts, they both type for exactly 16 minutes and finish together.
Alice types at 40 words per minute for 16 minutes:
Total words = 40 × 16 = 640 words
Step 2: Find how many words Sophie still needed to type when Alice started
Sophie had already typed 80 words before Alice started. After that, Sophie typed for the same 16 minutes.
Words remaining for Sophie = 640 − 80 = 560 words
Step 3: Find Sophie's typing speed
Sophie typed 560 words in the 16 minutes while Alice was also typing:
Sophie's speed = 560 ÷ 16 = 35 words per minute
Check: Sophie's total = 80 + 35 × 16 = 80 + 560 = 640 words ✓
Answer: Sophie types 35 words per minute
| Option | Speed | Check (560÷speed=16?) | |
|---|---|---|---|
| A | 30 | 560÷30≈18.7≠16 | ✗ |
| B | 32 | 560÷32=17.5≠16 | ✗ |
| C | 33 | 560÷33≈17≠16 | ✗ |
| D | 35 | 560÷35=16 ✓ | ✓ |
| E | 40 | 640÷16=40 — divided total words by Alice's time instead of remaining words. ✗ |