The y axis isn't labeled; we'll figure it out. Let's count square heights,
6-7) 3
7-8) 3
8-) 3
9) 3
10) 8
11) 8
12) 11
13) 11
14) 23
15) 19
16) 2
17) 2
18) 2
19) 2
Total 3+3+ 3+3+8+8+11+11+23+19+2+2+ 2+2 = 100
So each square height is ten mice.
We want the number less than 10 grams, that's the first four values.
10(3 + 3 + 3 + 3) = 10(12)=120
Answer: 120
