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disa [49]
2 years ago
7

8) A school community had planned to reduce the number of grade 9 students per class room by constructing additional class rooms

. However, they constructed 4 less rooms than they planned. As the result, the number of students per class 10 more than they planned. If there are 1200 grade nine students in the school, determine the current number of class rooms and the number of students per class.​
Mathematics
1 answer:
Allisa [31]2 years ago
7 0

Step-by-step explanation:

Let "c" be the original number of classrooms.

The 1200/c was the original number of students per classroom.

----

Equation:

1200/(c-4) = (1200/c)+10

Multiply thru by c(c-4)

---

1200c = 1200(c-4)+10c(c-4)

---

1200c = 1200c-4800 + 10c^2-40c

----

10c^2-40c-4800 = 0

c^2-4c-480 = 0

Factor:

(c-24)(c+20) = 0

---

Positive solution:

c = 24 (# of classrooms originaly planned)

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Step-by-step explanation:

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In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

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The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

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So below the 100-84 = 16th percentile and above the 10th percentile.

16th percentile:

This is the value of X when Z has a pvalue of 0.16. So X when Z = -0.995.

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X - 71.9 = -0.995*7.8

X = 64

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This is the value of X when Z has a pvalue of 0.1. So X when Z = -1.28.

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