Question

1. this dot plot shows the number of books read by kids in a class during the summer break. dot plot books read last summer number of books how many students are in the class? what is the range? what is the median? what is the average number of books the students read last summer?

Explanation:

1. Number of students in the class

Step1: Count dots per category

For 0 books: 4 dots; 1 book: 6 dots; 2 books: 3 dots; 3 books: 1 dot; 4 books: 2 dots; 5 books: 1 dot; 7 books: 1 dot; 8 books: 1 dot; 9 books: 1 dot.

Step2: Sum all dots

$4 + 6 + 3 + 1 + 2 + 1 + 1 + 1 + 1 = 20$

Step1: Identify max and min

Max books read: 9; Min books read: 0.

Step2: Calculate range

$Range = Max - Min = 9 - 0 = 9$

Step1: Order data (total 20 values, median is average of 10th and 11th term)

Data counts: 0(4), 1(6), 2(3), 3(1), 4(2), 5(1), 7(1), 8(1), 9(1). Cumulative: 0-4 (4), 1-10 (6), 2-13 (3), 3-14 (1), 4-16 (2), 5-17 (1), 7-18 (1), 8-19 (1), 9-20 (1).

Step2: Find 10th and 11th terms

10th term: 1; 11th term: 2. Median = $\frac{1 + 2}{2} = 1.5$? Wait, correction: Wait, cumulative for 0: 4, 1: 4+6=10, 2: 10+3=13. So 10th term is 1, 11th term is 2? No, wait, when n=20 (even), median is average of $\frac{20}{2}=10$th and $\frac{20}{2}+1=11$th term. Let's list positions:
1-4: 0s (positions 1-4)
5-10: 1s (positions 5-10)
11-13: 2s (positions 11-13)
14: 3
15-16: 4s
17: 5
18: 7
19: 8
20: 9
So 10th term: 1 (position 10), 11th term: 2 (position 11). Wait, no, position 10 is last of 1s (since 4+6=10), position 11 is first of 2s. So median = (1 + 2)/2 = 1.5? But maybe I miscounted. Wait original dot plot: 0 has 4, 1 has 6, 2 has 3, 3 has 1, 4 has 2, 5 has 1, 7 has 1, 8 has 1, 9 has 1. Total: 4+6=10, +3=13, +1=14, +2=16, +1=17, +1=18, +1=19, +1=20. So positions 1-4: 0; 5-10:1; 11-13:2; 14:3; 15-16:4; 17:5; 18:7; 19:8; 20:9. So 10th term is 1 (position 10), 11th term is 2 (position 11). So median is (1 + 2)/2 = 1.5? But maybe the initial handwritten 5 was wrong. Wait, maybe I misread the dot plot. Wait the dot plot: 0 has 4 dots, 1 has 6, 2 has 3, 3 has 1, 4 has 2, 5 has 1, 7 has 1, 8 has 1, 9 has 1. Let's recheck: 4+6=10, 10+3=13, 13+1=14, 14+2=16, 16+1=17, 17+1=18, 18+1=19, 19+1=20. Yes. So 10th term: 1 (since 5-10 are 1s), 11th term: 2 (11-13 are 2s). So median is (1 + 2)/2 = 1.5. But maybe the problem's handwritten 5 is incorrect. Wait, maybe I misread the dot plot. Wait the x-axis: 0,1,2,3,4,5,6,7,8,9. Dots: 0:4, 1:6, 2:3, 3:1, 4:2, 5:1, 7:1, 8:1, 9:1. So 6 is empty. So yes, median is 1.5. But maybe the user's handwritten 5 is a mistake. Alternatively, maybe I miscounted. Wait 4 (0s) +6 (1s)=10, so 10th term is 1, 11th term is 2 (since next is 2s: 3 dots, positions 11-13). So median is (1+2)/2=1.5.

Answer:

20

2. Range