11 Plus Exams Forum

Question from an independent school paper

Because she is sick in bed and has nothing better to do . Amy counts the number of buses which go past her house in every two minute period. She gets the following results.

Number of buses

0 1 2 3 4 5 6
Periods in which this number pass

15 17 12 6 6 5 1

i) How many buses did she count ?
ii) How long, at least would this have take her ?
iii) What is the most likely number of buses to pass Amy’s house in any two minute period?


Thank you in advance

a) how many buses did she count?

Add busses in each period.

0x15=0
+
1x17=17
+
2x12=24
+
3x6=18
+
4x6=24
+
5x5=25
+
6x1=6

= 114 buses.

How long would it have taken?
= (Total number of periods) x (duration of each period)
= (15+17+12+6+6+5+1) x (2 minutes)
= 62 x 2
= 124 minutes

Most likely number of buses in any period?

= 1 (because it happened 17 times)

hope this helps.

regards.

Uh? I'm assuming the layout went wonky and the question is telling us that in 15 two minute periods 0 buses went past, in 17 2 minute periods 1 bus went past, in 12 2 minute periods 3 buses went past etc etc.

So the number of buses she counted was 15x0 plus 17 x 1 plus 12 x 2 etc etc.

How long, at least, did this take her - well each period was 2 minutes and she counted for 15+17+12+6+6+5+1 periods. Then multiply the number of periods by 2 minutes.

Most likely number of buses to pass is 1, as this is the number that went past during 17 of the time periods, and 1 is the number that occurred most frequently as 17 is the highest number of periods to have the same number of buses passing.

Hope that makes sense.

Oops someone else replied at same time as me!!

Hello

Thank you to both of you The tabulation didn't work out - sorry.