In a certain class there are 12 boys and 18 girls. If the class average for an algebra exam is 90 and the boys' average score is 87, what is the girls' average score?
(12*87+18x)/(12+18) = 90
Now just solve for x
X is 92
The ratio of boys to girls is 12 to 18 if they are 87 girls how many boys are there
Well, if we take into consideration that girls are usually smarter than boys... just kidding! Let's solve this math problem together.
We know that the class average is 90, and the boys' average score is 87. In order to find the girls' average score, we can use the concept of weighted averages.
The class average is the overall average of all the students combined. Since there are 12 boys and 18 girls, the boys' scores make up a smaller proportion of the class average compared to the girls' scores.
To find the girls' average score, we need to calculate the weighted average using the formula:
(weight of boys' scores * boys' average) + (weight of girls' scores * girls' average) = class average
The weights of the boys' and girls' scores are determined by the number of boys and girls in the class. In this case, since there are 12 boys and 18 girls, the weights would be 12/30 and 18/30, respectively.
So, let's plug in the values we know:
(12/30 * 87) + (18/30 * girls' average) = 90
Now we can solve for the girls' average score:
(12/30 * 87) + (18/30 * girls' average) = 90
Simplifying this equation will give us the girls' average score.
And remember, even if the boys' average is lower, it doesn't mean they are any less awesome!
To find the girls' average score, we need to first calculate the total score of the whole class.
We know that the class average is 90, which means that the sum of all the students' scores divided by the number of students is 90.
To find the total sum of scores, we multiply the class average by the total number of students:
Total score = class average * total number of students
Total score = 90 * (12 boys + 18 girls)
= 90 * 30
= 2700
Now, let's calculate the total score of the boys:
Total score of boys = boys' average score * number of boys
= 87 * 12
= 1044
To find the total score of the girls, we subtract the total score of the boys from the total score of the class:
Total score of girls = Total score - Total score of boys
= 2700 - 1044
= 1656
Finally, we need to calculate the girls' average score:
Girls' average score = Total score of girls / Number of girls
= 1656 / 18
= 92
Therefore, the girls' average score is 92.