A class of 28 students has 13 boys and 15 girls. What is the ratio of girls to boys in the class? 15:28 15:13 13:15 13:28
PREVIOUS ent performs the following estimations. 24 + 190 = 210 151 +319=470 974 + 1,022 = 1,990 Based on these estimations, which of the following is the student’s estimate of 452 +5,017? 5,470 5,500 5,450 5,400
The Correct Answer and Explanation is:
Question 1: A class of 28 students has 13 boys and 15 girls. What is the ratio of girls to boys in the class?
Correct Answer: 15:13
Explanation:
A ratio is a comparison between two quantities. In this case, the problem asks for the ratio of girls to boys, meaning we are comparing the number of girls first to the number of boys second.
From the problem:
- Number of girls = 15
- Number of boys = 13
So the ratio of girls to boys is:
15:13
This is a part-to-part comparison because it compares two parts of the whole (girls and boys). If the question had asked for the ratio of girls to the total number of students, that would be a part-to-whole ratio (15:28). But since it specifically asks for girls to boys, the correct answer is:
15:13
Question 2: A student performs the following estimations:
- 24 + 190 = 210 (actual: 214)
- 151 + 319 = 470 (actual: 470)
- 974 + 1,022 = 1,990 (actual: 1,996)
Based on these, what is the best estimate for 452 + 5,017?
Correct Answer: 5,500
Explanation:
Estimation in addition typically involves rounding numbers to the nearest ten, hundred, or thousand depending on the numbers involved. Let’s analyze the student’s pattern:
- 24 + 190 = 210
→ Rounded 24 to 20 and 190 to 190 → 20 + 190 = 210 - 151 + 319 = 470
→ Rounded 151 to 150 and 319 to 320 → 150 + 320 = 470 - 974 + 1,022 = 1,990
→ Rounded 974 to 1,000 and 1,022 to 1,000 → 1,000 + 1,000 = 2,000, but the student estimated slightly under at 1,990, possibly for simplicity.
So the student consistently uses rounding to the nearest 10, 50, or 100, often rounding slightly down.
Now apply this to 452 + 5,017:
- 452 rounds to 500 (or 450, depending on how aggressive the rounding is)
- 5,017 rounds to 5,000
→ 500 + 5,000 = 5,500
This fits with the student’s previous estimation style.
Therefore, the best estimate the student would give is:
5,500