CoormaBak9

2021-02-02

Sofia's 4th grade class has a spelling list organized by subject. The spelling list includes 170 words about history, 75 words about science, 60 words about math, and 55 words about geography. Each week, Sofia's teacher tests her on 15 words from the list. Sofia's class has already had 7 weeks of spelling tests. How many more words will Sofia be tested on before the end of the year?

liingliing8

Solution:
Total words are 170 + 75+60+55=360.
Each week, Sofia is test with 15 words from the list.
Total number of weeks it will take to finish the test is 24.
Average number of weeks in a year is 25 approximately.
Seven weeks are already over, that means $15×7=105$ words are covered from the list. Conclusion:
Remaining words are 360—105=255.
These words can be covered in a group of 15 in a week, so $\frac{255}{15}=17$ are the number of weeks.
Therefore, the number of words that Sofia will be tested on before the end of the year is 255.

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