Puzzle 93
Last week I travelled from London to Leeds, a distance I measured as 174 miles.
I started at 9.15am and completed the journey with an average speed of 40 miles per hour.
On the way back, in the evening, I travelled exactly the same route, starting at 5.15pm. The traffic was light, and I completed the journey with an average speed of 60 miles per hour.
What was the overall average speed for the round trip?
The answer is not 50 mph.
Puzzle Copyright © Kevin Stone
workings
hint
answer
print
Share link: www.brainbashers.com/puzzle/ztah
Hint
Remember that Time = Distance ÷ Speed, and Speed = Distance ÷ Time.
Answer
48 miles per hour.
Reasoning
Using:
Time = Distance ÷ Speed
Tpeed = Distance ÷ Time
The outward journey took 174 miles ÷ 40 mph = 4.35 hours.
The return journey took 174 miles ÷ 60 mph = 2.9 hours.
So I travelled a total of 2 x 174 = 348 miles. I did this in a total of 4.35 + 2.9 = 7.25 hours.
My overall average speed was therefore 348 miles ÷ 7.25 hours = 48 miles per hour.
Puzzle 94
Questionnaire - Logic Puzzles
Here is the latest BrainBashers questionnaire, how well can you do?
Q1. The first question with A as the correct answer is:
A. Q2
B. Q3
C. Q4
Q2. The answer that appears most often is:
A. C
B. B
C. A
Q3. The answer to Q1 is:
A. B
B. A
C. C
Q4. The answer that appears least often is:
A. A
B. C
C. B
Puzzle Copyright © Kevin Stone
workings
hint
answers
print
Share link: www.brainbashers.com/puzzle/zoan
Answers
Q1. B
Q2. B
Q3. A
Q4. B
Reasoning
Q1 can't have A as its answer (otherwise it would contradict itself).
If Q1's answer was C (meaning Q4's answer was A), then Q3's answer would be C. However, Q2's answer should now be A, but this isn't allowed by Q1 (as Q4 is the first answer with A). This is a contradiction.
Therefore, Q1's answer is B (meaning Q3's answer is A).
For Q2's answer to be C, Q4's answer would have to be A, which would contradict Q4. Therefore, Q2's answer is B making Q4's answer B.
Puzzle 95
My local bus company has recently expanded and no longer has enough room inside its garage for all of its buses.
Twelve of their buses have to be stored outside.
If they decide to increase their garage space by 40% they will have enough room for all of their current buses, plus enough room to store another twelve in the future.
How many buses does the company currently own?
Puzzle Copyright © Kevin Stone
workings
hint
answer
print
Share link: www.brainbashers.com/puzzle/zwol
Hint
Think about the 40% and how many buses that represents.
Answer
72 buses.
Reasoning
If they increase the garage space by 40% this will give them enough room to hold the 12 buses that are currently outside, plus 12 more buses in the future.
Therefore, the 40% increase is enough space for 24 buses.
This means that 40% of the current garage capacity is 24 buses.
So 10% of the current garage capacity is 6 buses.
And 100% of the current garage capacity is 60 buses.
If we add the 12 buses stored outside we have a total of 72 buses.
Double-Checking
They currently have 72 buses, 12 of which are outside, so 60 are inside. Increasing their garage space (60 buses) by 40% will give room for 84 buses. Which is the 72 they currently have, with spaces for 12 more buses in the future. This confirms the answer.
Puzzle 96
Classical Collection - Logic Puzzles
In my collection of classical music, I have a range of pieces that last 6, 7, 8 and 9 minutes.
The piece by Bach lasts 8 minutes, and the CD lasts longer than the piece by Holst.
The piece on DAT tape is longer than the piece by Beethoven.
The single lasts 7 minutes, and the album does not contain any Holst.
The piece by Butler is on the DAT tape.
Can you determine which piece of music is in which format, and how long each lasts?
Puzzle Copyright © Kevin Stone
workings
hint
answer
print
Share link: www.brainbashers.com/puzzle/ztox
Hint
Look at the piece by Bach, and the single.
Answer
Composer Format Length
Beethoven album 6
Holst single 7
Bach CD 8
Butler DAT 9
Reasoning
By (1), the piece by Bach lasts 8 minutes. By (3), the single lasts 7 minutes.
Composer Format Length
6
single 7
Bach 8
9
By (4), the piece by Butler is on the DAT tape. But, by (2), this can't be the shortest, so it must be 9 minutes long.
Composer Format Length
6
single 7
Bach 8
Butler DAT 9
By (1), the CD can't be the shortest, so must be 8 minutes long.
Composer Format Length
6
single 7
Bach CD 8
Butler DAT 9
The album must therefore be 6 minutes long, and by (3) doesn't contain any Holst.
Composer Format Length
album 6
Holst single 7
Bach CD 8
Butler DAT 9
Which means that the album was the piece by Beethoven.
Composer Format Length
Beethoven album 6
Holst single 7
Bach CD 8
Butler DAT 9
< previous next >
Note: BrainBashers has a Dark Mode option – I recommend not using your browser's dark mode or extensions for BrainBashers
