Answer:
The mean score for all students on the quiz was 86.
Step-by-step explanation:
This question is solved by a weighed average.
To find the weighed average, we add the values multiplied by their weight, and after that we divide by the sum of weights.
In this problem, we have that:
Mr. Spears had 20 students in his class with a mean score of 80.
So 80 has a weight of 20.
Mrs. Guyton's class of 30 students had a mean score of 90.
So 90 has a weight of 30.
Overall, what was the mean score for all students on the quiz
The mean score for all students on the quiz was 86.
Answer:
- 1 bus, 72 vans
- $6960 is the minimum cost
Step-by-step explanation:
A bus costs over $19 per student; a van costs less than $12 per student. The required number of students could be transported by 81 vans, but that requires 81 chaperones.
Since there are only 80, and a bus requires fewer chaperones per student, we can reduce the number of required chaperones to an acceptable level by employing one bus. 1 bus replaces 9 vans, and requires 1 less chaperone than 9 vans.
The minimum cost is 1 bus and 72 vans. That cost is $1200 +72×$80 = $6960.
It's quite simple. Look:
Lets let S- be the age of Sally and B- can be the age of Beth
S+B=60
S-6=3(B-6)
S-6=3B-18
S=3B-18+6
S=3B-12
3B-12+B=60
4B=60+12
4B=72
B=72/4
B=18
B=60-18
B=42
The ages are (B)18 and (S)42
Hope this helps!! :)