After visiting one of my very old relatives, I travelled home in their old jalopy. The car was old and battered, it had a leak from the petrol tank, and I was stuck in second gear.
This meant that I could only travel along at a steady 30 miles per hour and managed a paltry 20 miles per gallon of fuel.
At the start of the journey, I had placed exactly 10 gallons of fuel into the tank. I knew though, that the fuel tank lost fuel at the rate of half a gallon per hour.
Just as I arrived home, the car stopped because it had run out of fuel and I had only just made it.
How far was it from my relative's house to my home?
At the recent BrainBashers downhill mountain bike race, four entrants entered the challenging slalom event.
Alex finished in first position. The entrant wearing number #2 wore red, but Drew didn't wear yellow. The person in last place wore blue, and Stevie wore number #1. Glen beat Stevie, and the person who finished in second wore number #3. The entrant in yellow beat the entrant in green. Only one of the entrants wore the same number as their final position.
Can you determine who finished where, the number, and colour they each wore?
Hint
Start by looking at where Alex finished, and where the person who wore #3 finished, and then use clue (6).
Answer Pos Name Wore Colour
1 Alex #2 red
2 Glen #3 yellow
3 Stevie #1 green
4 Drew #4 blue
Reasoning
The four colours were: blue, green, red, yellow.
The four contestants were: Alex, Drew, Glen, Stevie.
By (1), Alex was first.
1 Alex
2
3
4
By (4), the person who was second wore number #3.
1 Alex
2 #3
3
4
Looking at (6):
- first place (Alex) can't have worn #1, because, by (3), Stevie wore #1
- second place wore #3
- third place can't have worn #3, because it was worn by second place
- fourth place is the only entrant who could have worn the same number as their final position
Therefore, Stevie finished in third, and Alex wore #2.
1 Alex #2
2 #3
3 Stevie #1
4 #4
By (2), Alex wore red. By (3), the person wearing blue was last.
1 Alex #2 red
2 #3
3 Stevie #1
4 #4 blue
By (5), yellow beat green.
1 Alex #2 red
2 #3 yellow
3 Stevie #1 green
4 #4 blue
By (4), Glen beat Stevie.
1 Alex #2 red
2 Glen #3 yellow
3 Stevie #1 green
4 #4 blue
Leaving Drew in last place.
1 Alex #2 red
2 Glen #3 yellow
3 Stevie #1 green
4 Drew #4 blue
Reasoning
In 36 hours, Alex could empty 2 lots of bookshelves, Billie could also empty 2 lots of bookshelves, and Drew could refill 1 lot of bookshelves.
So, 2 + 2 − 1 = 3 lots of bookshelves in 36 hours. Which is 12 hours for one lot of bookshelves.
Alternative Reasoning
Alex and Billie can each empty 1/18 of the bookshelves in 1 hour, but Drew will refill 1/36 of the bookshelves in one hour.
So in one hour we have 1/18 + 1/18 − 1/36 = 1/12.
So it would take 12 hours to empty the bookshelves.
