Answer:
A. 36
Step-by-step explanation:
We are given a total of 176 interviewed by Oliver and a total of 140 interviewed by Jenny. To find how many more 10th graders than 9th graders were interviewed, subtract the totals given
176 - 140 = 36
This is how we came to the answer:
We are given 70% of the 10th-grade and 30% of the 9th-grade with a total of 176 for Oliver.
While we're given 75% of the 9th-grade class and 25% of the 10th-grade with a total of 140 interviewed by Jenny
Oliver's Interviewees
10-graders
Firstly, let's find what the number of 9th-graders was interviewed by Oliver; find the percentage of the 9th-graders by the total;
70% of 176 =
Cross multiply
123.2 were 10-graders interviewed by Oliver
9th-graders
Now, to find the number of 9th-graders was interviewed by Oliver; find the percentage of the 9th-graders by the total;
30% of 176 =
Cross multiply
52.8 were 9th-graders interviewed by Oliver
Jenny's Interviewees
9th-graders
Firstly, let's find what the number of 9th-graders was interviewed by Jenney; find the percentage of the 9th-graders by the total;
75% of 140 =
Cross multiply
105 students were 9th-graders interviewed by Jenney.
10th-graders
Now, to find the number of 10th-graders was interviewed by Jenney; find the percentage of the 10th-graders by the total;
25% of 140 =
Cross multiply
35 students were 10th-graders interviewed by Jenney.
Total calculation
Use the results and sum them up by 9th-grade plus 9th-grade and 10th-grade plus 10-grade. Then subtract the amount gotten from 9th-grade away from the amount gotten from 10th-grade;
Oliver's 9th-grade = 52.8
Jenny's 9th-grade = 105
105 + 52.8 = 157.8
Oliver's 10th-grade = 123.2
Jenny's 10th-grade = 35
123.2 + 35 = 158.2
Total calculation: 158. 2 - 157.8 = 0.4
Therefore, there are 36 more 10th than 9th.
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⇒⇒⇒⇒ rule (2)
⇒⇒⇒⇒ rule (1) and rule (2)
⇒⇒⇒⇒ rule (3)