At my local farmer's merchant, you can buy chicken feed for £4 per tonne, pig feed for £3 per tonne, and cattle feed for 40p per tonne. The feed can only be purchased by the tonne, and part tonnes aren't sold.
Last week I bought some animal feed, and luckily I managed to buy exactly 100 tonnes for exactly £100. How much of each feed did I buy?
Hint
What must the number of tonnes of cattle feed be a multiple of?
Answer
I bought 8 tonnes of chicken feed, 12 tonnes of pig feed, and 80 tonnes of cattle feed.
Reasoning
The number of tonnes of cattle feed must be a multiple of 5, because we need to have a whole number of pounds (5 x 0.40).
If all 100 tonnes was cattle feed, the cost would have been £40, which isn't enough.
If 95 tonnes was cattle feed the cost would have been £38, and the remaining 5 tonnes of (the most expensive) chicken feed at £20, gives a total of £58, which isn't enough.
If 90 tonnes was cattle feed the cost would have been £36, and the remaining 10 tonnes of (the most expensive) chicken feed at £40, gives a total of £76, which isn't enough.
If 85 tonnes was cattle feed the cost would have been £34, and the remaining 15 tonnes of (the most expensive) chicken feed at £60, gives a total of £94, which isn't enough.
If 80 tonnes was cattle feed the cost would have been £32, and the remaining 20 tonnes of (the most expensive) chicken feed at £80, gives a total of £112. So, this might be a possible answer …
We need 20 tonnes of chicken feed and pig feed to equal £68, so let's reduce the chicken feed until it works.
Hint
Light travels around 186,000 miles each second.
Answer
Miles that light can travel in 3 minutes.
There are 31,536,000 seconds in a typical year, and light can travel about 33,530,831 miles in 3 minutes.
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Puzzle 19
Can you find the book titles hidden in these phrases?
ROME OR OSLO? ANDREW, JULIE, TO VISIT. WARM TOO FEW, THE SUBWORLD SNEEZES AN I MALL? SHOPS, FAR MALLS? GO NEXT, GO! WITHOUT OTHER I DWINDLE. GO! WATER. SHIP, BOAT. STORM! DOWN RAIN! BRAVERY IN A NEW AGE, WORLD'S HOPE.
For each word in the title, new letters are added of the same length, and then the spacing is changed, and punctuation is added.
For example:
BOOK TITLE
BOOK 1234 TITLE 12345
BOOK NIGH TITLE APTUP
BOOKNIGHTITLEAPTUP
BOO, KNIGHT. IT LEAPT UP!
Answers
ROME OR OSLO? ANDREW, JULIE, TO VISIT.
ROMEO ROSLO AND REW JULIET OVISIT
= ROMEO AND JULIET
WARM TOO FEW, THE SUBWORLD SNEEZES
WAR MTO OF EW THE SUB WORLDS NEEZES
= WAR OF THE WORLDS
AN I MALL? SHOPS, FAR MALLS?
ANIMAL LSHOPS FARM ALLS
=ANIMAL FARM
GO NEXT, GO! WITHOUT OTHER I DWINDLE. GO!
GONE XTGO WITH OUTO THE RID WIND LEGO
= GONE WITH THE WIND
WATER. SHIP, BOAT. STORM! DOWN RAIN!
WATERSHIP BOATSTORM DOWN RAIN
= WATERSHIP DOWN
BRAVERY IN A NEW AGE, WORLD'S HOPE.
BRAVE RYINA NEW AGE WORLD SHOPE
= BRAVE NEW WORLD
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Puzzle 20
Each empty white square in the grid contains one of the numbers 1, 2, 3, …, 8. Each of the horizontal and vertical equations must be true, and each number must be used exactly once.
