Elder brother and younger brother each chooses a time between 5 pm and 6 pm
and arrives at the school main gate. They agreed that if one had waited for more
than 15 minutes, he could go home first. Otherwise they would go home togrther.
Find the probability that they go home together.
Maths!!! Probability!!!
2010-04-04 10:19 pm
回答 (1)
2010-04-04 10:47 pm
✔ 最佳答案
Draw a square (1*1) Let the x-axis (from 5 pm to 6 pm) represents Elder brother and the y-axis (from 5 pm to 6 pm) represents younger brother.Notive that (0,0)=(5 pm,5 pm) (1,1)=(6 pm,6 pm)
Then draw a straight line connect (0,0.25) and (0.75,1). Draw another line connect (0.25,0) and (1,0.75). Then all the points which fall into the two triangles represent that they do not meet together.
So the probability that they go home together
=(3/4)(3/4)=9/16
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