Answer:
. In other words, there number of girls is
.
Step-by-step explanation:
The average of a number of measurements is equal to the sum of these measurements over the number of measurements.
.
Rewrite to obtain:
.
For this question:
.
.
Therefore:
.
On the other hand, there are
boys and girls in total. Using the formula for average:
.
From the question, this average should be equal to
. In other words:
.
Solve this equation for
to obtain:
.
.
.
In other words, the number of girls here is
.
80 because of you cross multiply 6 times x and 30 times 16 you get 480 and 6 divided by 480 is 80
6/16=30/?
6x=480
Divided by 6
?=80
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Option C
Math teacher would need to buy 130 prizes
<em><u>Solution:</u></em>
Given that,
Math teacher currently has 109 students and the box has 88 prizes in it
The math teacher likes to keep at least twice as many prizes in the box as she has students
So, she wants the number of prizes to be twice the number of students
Therefore,
number of prizes = 2 x 109 students
number of prizes = 2 x 109 = 218 prizes
The box has 88 prizes in it
Therefore, number of prizes she would need to buy is:
⇒ 218 - 88 = 130
Thus she would need to buy 130 prizes