Answer: 385
Step-by-step explanation:
Mean the three groups of 10 kids=35
Total weight of 3 groups (10x35)=350
Mean weight of 3 groups and one boy ( 35 + 350)=385
5 : -16
6 : -19
7 : -22
8 : -25
9 : -28
10: -31
11 : -34
12: -37
13: -40
14 : -43
15 : -46
16 : - 49
17 : - 52
18 : - 55
19 : - 58
20: - 61
21 : - 64
22: -67
23: -70
23rd term : is -70