Mathematics
Junior Kangaroo
2023
19

19

A group of 40 boys and 28 girls stand hand in hand in a circle facing inwards. Exactly 18 of the boys give their right hand to a girl. How many boys give their left hand to a girl?

A. 12

B. 14

C. 18

D. 20

E. 22

Answer

C. 18

SOLUTIOn

We are told that 18 boys give their right hand to a girl and that there are 40 boys in the circle in total. Therefore 22 boys give their right hand to a boy. Since all the children are facing inwards, this means that all the boys who have a boy giving them their right hand, will in return be giving a boy their left hand. Hence 22 boys give their left hand to a boy. Therefore there will be 18 boys who give their left hand to a girl.

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