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Question
primary 6 | Maths
| Data Analysis
3 Answers Below
Anyone can contribute an answer, even non-tutors.
How to solve, need to list all of the combinations is it, ????? Don’t understand???
We work from total hours for girls can use the studio.
2 hour with 5 girls each time, so the total hours spend by 5 girls is 5×2=10hour.
Then average it with 8 girls since all of them spend equal amount of time there.
Step①
U can do the listing for all combinations as the number is not that big
Step②
change the number of girls played in each round from 5
to 6 3 4 2 (8 remain , no change)
Still can list N figure out the answer
Step③
change the total. number of girls from 8
to 7 6 (5 remain , no change)
Still can list N figure out the answer
Step④
Find the pattern from step①~③
Step⑤
Figure out the physical meaning described by AC Lim
Understand it is pretty tedious , but wish you can get the idea from this practice to fully understand this type of questions.
Similar Q in
2017 PSLE
5 computers are available so there are 5 slots.
The computers are always occupied/being used in the 2 hours. We consider time taken for the girls take turns (standing up, letting the next girl take their place) as negligible or zero.
In the same 2 hours, each computer is being played.
Now if we considered the total number of hours played, it is 2 × 5 = 10 hours.
This is as though we count the hours for each computer separately then add them together.
Then divide the total hours equally among 8 girls since each girl has equal playing time.
You don't really need to worry about the order which they take turns or the sequence they play.
The concept here is known as man-hours
See 3 Answers
Every 15 mins change combination. Hope to clear your doubts.
Likewise, you need to think this way. Only 2 hour at dance studio, each time 5 girls, total spend in studio 5×2=10 hours.
8 girls spend 10 hours.
1 girls spend 10/8= 1.25 hours = 1hr15mins
The only part is you need to consider the TOTAL number of hours spent dancing by the girls
You can also make it like every 1 minute they change and eventually the sequence/order will repeat every 8 minutes.
Everyone will still get 75 minutes of dancing in the end.
Example: 4 students book badminton court for 1 hour. Each time 2 students play.
By intuitive, 1st 2 students played ½ hour then next 2 students played another ½ hours.
Each of them played ½ hour
By average...
2 students only play in 1 hour, total hours = 2×1 hour = 2 hours
4 students → 2 hr
1 student → 2/4 = ½ hour.
I'll give you a simpler example first.
① If there are 2 hours available to to play on 1 computer and there is only 1 girl, this girl can play for the full 2 hours.
②However, if there are 2 girls now and they have to share the time equally, then each girl can only play for ½ the total time.
2 hours × ½ = 1 hour
③ If there are 3 girls now then each girl can only play for ⅓ of the 2 hours.
2 hours × ⅓ = ⅔ hours = 40 minutes.
④If there are 2 computers now but still 3 girls, then ⅔ of the time.
2 hours × ⅔ = 1⅓ hours = 1h 20 min
⑤ If there are 4 computers now but 7 girls, then 4/7 of the time.
So, if there are 5 computers but 8 girls, each girl only gets to play ⅝ of the time.
2 hours × ⅝ = 5/4 hours = 1¼ hours
= 1 hour 15 min