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primary 5 | Maths
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Tried to use ratio method with total question unchanged. But am getting 1u=14/11. So the final answer(20u * 11/14) seems needs to be rounded? Felt it's wrong...
Date Posted: 10 months ago
Views: 101
Total unchanged
After the first hour,
Answered : Not Answered : Total
1 : 2 : 3
In the end,
Answered : Not answered : Total
4 : 1 : 5
Change both totals to 15
So,
After the first hour,
Answered : Not Answered : Total
1 : 2 : 3
5 : 10 : 15
After answering another 14 questions,
Answered : Not answered : Total
4 : 1 : 5
12 : 3 : 15
We can see that answered questions increased by 7 units (12 - 5 = 7)
So 7 units = 14
1 unit = 14 ÷ 2 = 7
After the first hour,
Answered : Not Answered : Total
1 : 2 : 3
In the end,
Answered : Not answered : Total
4 : 1 : 5
Change both totals to 15
So,
After the first hour,
Answered : Not Answered : Total
1 : 2 : 3
5 : 10 : 15
After answering another 14 questions,
Answered : Not answered : Total
4 : 1 : 5
12 : 3 : 15
We can see that answered questions increased by 7 units (12 - 5 = 7)
So 7 units = 14
1 unit = 14 ÷ 2 = 7
Number of questions in the test
= 15 × 2
= 30
= 15 × 2
= 30
See 1 Answer
Refer to main comments section for working and explanation.
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