Hint
How many students study chemistry and physics, but not biology?
Answer
500 students.
Reasoning
The answer is more easily seen if three intersecting circles are drawn, and the numbers inside each section are worked out.
We know that 73 students study all three disciplines, which allows us to work out the numbers.
97 students study chemistry and physics, so 97 − 73 = 24 study just chemistry and physics.
138 students study physics and biology, so 138 − 73 = 65 study just physics and biology.
152 students study chemistry and biology, so 152 − 73 = 79 study just chemistry and biology.
280 students study chemistry, so 280 − 73 − 24 − 79 = 104 study just chemistry.
254 students study physics, so 254 − 73 − 24 − 65 = 92 study just physics.
280 students study biology, 280 − 73 − 65 − 79 = 63 study just biology.
For a total of: 104 + 92 + 63 + 24 + 65 + 79 + 73 = 500 students.
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Puzzle 742
Can you find five countries hidden in the following paragraph:
Dominic had a certain way with animals, he could almost talk to them. By tickling it under the chin, a rabbit would roll over and let its belly be tickled. This technique was sometimes used to good effect in gaining trust, and allowed a vital yearly treatment to be performed safely. The removal of nits. Using a vet approved shampoo to clean the fur (and not a blend of malt and water!).
Hint
One of the countries begins with the letter M.
Answers
Chad, China, Togo, Italy, Malta.
Domini[c had] a certain way with animals, he could almost talk to them. By tickling it under the [chin, a] rabbit would roll over and let its belly be tickled. This technique was sometimes used [to go]od effect in gaining trust, and allowed a v[ital y]early treatment to be performed safely. The removal of nits. Using a vet approved shampoo to clean the fur (and not a blend of [malt a]nd water!).
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Puzzle 743
Here is a well-known proverb with the consonants removed. What is the proverb?
