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Taya2010 [7]
3 years ago
10

18% of the the students at a school are in year 8 and 16% of the students are in year 9. If the school has 126 tera 8 students,

determine the number of year 9 students.​
Mathematics
1 answer:
yarga [219]3 years ago
5 0

Answer:

112

Step-by-step explanation:

The general form of all percentage questions is: the chunk= (some percentage) (of the whole), or c=p*w

We know that 18% of students are 8th grade and that is 126 students, so p = 0.18 and c=126 (126 students are 18% of the whole school)

126 = (0.18)w, divide both sides by 0.18

126/(0.18) = w = 700

9th graders are 16% of the school or 16% of 700 students

c = (0.16) 700 = 112 students

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Step-by-step explanation:

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How large a sample is needed in order to be 98% confident that the sample proportion will not differ from the true proportion by more than 2%?

This is n for which M = 0.02. So

M = z\sqrt{\frac{\pi(1-\pi)}{n}}

0.02 = 2.327\sqrt{\frac{0.08*0.92}{n}}

0.02\sqrt{n} = 2.327\sqrt{0.08*0.92}

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