# Help with BMAT 2013 Section 1 Q25 and Q32

Thread starter 4 years ago
#1
Hello! I can't seem to understand the solutions to these questions. I have listed down the questions, but if you want to just have a look at the paper, I have included the link to it as well.

Q25. My neighbour has two 24-hour digital clocks in her living room. One of them is always 25 minutes fast and the other is always 16 minutes slow. Why she keeps them like this I don't know, but it does mean that once every day, for two successive minutes, the eight digits displayed on the two clocks are all different.

What is the only digit that does NOT appear on either clock during the two successive minutes when all eight digits are different?

A. 3
B. 4 this is the correct answer
C. 5
D. 6
E. 7
F. 8

This question is based off a passage, but here is key information you need to know

- 20% of young people now report using cannabis at least once a week
- Cannabis users are 41% more likely to have any psychosis than those who had never used the drug

Q32. In 10 000 typical young people, if 1% of non-cannabis users develop psychosis, how many cannabis users would be expected to develop psychosis?

A. 20
B. 28 this is the correct answer
C. 41
D. 112
E. 141

In a solution book which I've read, it says
If 1% of non-cannabis users develop psychosis, and cannabis users are 41% more likely to have any psychosis than those who had never used the drug, 1.41% of cannabis users in the sample will have psychosis.

Now my questions is how do you get the 1.41%??

Thank you so much to whoever answers this, you are amazing and a genius if you can explain it <3
0
4 years ago
#2
Hi! I just did the questions today and here are my solutions:

Q25: The two clocks are 41 minutes apart. If we consider the hour digit first, the only possible outcome is 19 and 20. We are left with 3,4,5,6,7,8. Then we consider the minute digit. Only 3,4 and 5 are possible for the first number, and 41 minutes apart means 3 and 5. We are left with 4, 6, 7, 8. And so the two successive minutes are 19:56, 20:37 and 19:57, 20:38. 4 does not appear.

Q32: 20% of young people use cannabis, so in 10000 young people, 2000 use cannabis. It says 1% of non-cannabis users develop psychosis and cannabis users are 41% more likely than non-cannabis users. So 1*(1+0.41) = 1.41% of the cannabis users develop psychosis. 2000*1.41%=28
1
Thread starter 4 years ago
#3
(Original post by ArGu)
Hi! I just did the questions today and here are my solutions:

Q25: The two clocks are 41 minutes apart. If we consider the hour digit first, the only possible outcome is 19 and 20. We are left with 3,4,5,6,7,8. Then we consider the minute digit. Only 3,4 and 5 are possible for the first number, and 41 minutes apart means 3 and 5. We are left with 4, 6, 7, 8. And so the two successive minutes are 19:56, 20:37 and 19:57, 20:38. 4 does not appear.

Q32: 20% of young people use cannabis, so in 10000 young people, 2000 use cannabis. It says 1% of non-cannabis users develop psychosis and cannabis users are 41% more likely than non-cannabis users. So 1*(1+0.41) = 1.41% of the cannabis users develop psychosis. 2000*1.41%=28
Thank you so much for the help!! I really understood the clock one.

I would just like to clarify the cannabis one - I'm not really sure about the equation. So for example if they said 3% of non-cannabis users develop psychosis, and cannabis users are 41% more likely than non-cannabis users, would that mean the equation is 3*(1+0.41) ?

Really appreciate your help!!
0
4 years ago
#4
(Original post by gemchew)
Thank you so much for the help!! I really understood the clock one.

I would just like to clarify the cannabis one - I'm not really sure about the equation. So for example if they said 3% of non-cannabis users develop psychosis, and cannabis users are 41% more likely than non-cannabis users, would that mean the equation is 3*(1+0.41) ?

Really appreciate your help!!
Yes you are right. 41% is comparing with the non-cannabis users.
0
3 years ago
#5
(Original post by ArGu)
Hi! I just did the questions today and here are my solutions:

Q25: The two clocks are 41 minutes apart. If we consider the hour digit first, the only possible outcome is 19 and 20. We are left with 3,4,5,6,7,8. Then we consider the minute digit. Only 3,4 and 5 are possible for the first number, and 41 minutes apart means 3 and 5. We are left with 4, 6, 7, 8. And so the two successive minutes are 19:56, 20:37 and 19:57, 20:38. 4 does not appear.

Q32: 20% of young people use cannabis, so in 10000 young people, 2000 use cannabis. It says 1% of non-cannabis users develop psychosis and cannabis users are 41% more likely than non-cannabis users. So 1*(1+0.41) = 1.41% of the cannabis users develop psychosis. 2000*1.41%=28
(Original post by ArGu)
Hi! I just did the questions today and here are my solutions:

Q25: The two clocks are 41 minutes apart. If we consider the hour digit first, the only possible outcome is 19 and 20. We are left with 3,4,5,6,7,8. Then we consider the minute digit. Only 3,4 and 5 are possible for the first number, and 41 minutes apart means 3 and 5. We are left with 4, 6, 7, 8. And so the two successive minutes are 19:56, 20:37 and 19:57, 20:38. 4 does not appear.

Q32: 20% of young people use cannabis, so in 10000 young people, 2000 use cannabis. It says 1% of non-cannabis users develop psychosis and cannabis users are 41% more likely than non-cannabis users. So 1*(1+0.41) = 1.41% of the cannabis users develop psychosis. 2000*1.41%=28
Hi, sorry to bring this up again, but how did you get 19 and 20? I don't quite get that
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