Читать книгу The Ultimate Mathematical Challenge: Over 365 puzzles to test your wits and excite your mind - Литагент HarperCollins USD, F. M. L. Thompson - Страница 17
Оглавление43. Easter eggs
Mary has three brothers and four sisters.
If they, and Mary, all buy each other an Easter egg, how many eggs will be bought?
44. A shape sum
In the sum shown, different shapes represent different digits.
What digit does the square represent?
45. The pages of a newspaper
A newspaper has thirty-six pages.
Which other pages are on the same sheet as page 10?
46. The sum of two primes
The number 12 345 can be expressed as the sum of two primes in exactly one way.
What is the larger of the two primes?
47. A perimeter
The diagram shows three touching circles, each of radius 5 cm, and a line touching two of them.
What is the total length of the perimeter of the shaded region?
48. The oldest tree
Today the combined age of three oak trees is exactly 900 years. When the youngest tree has reached the present age of the middle tree, the middle tree will be the present age of the oldest tree and four times the present age of the youngest tree.
What is the present age of the oldest tree?
49. Who’s done their homework?
Miss Spelling, the English teacher, asked five of her students how many of the five of them had done their homework the day before. Daniel said none, Ellen said only one, Cara said exactly two, Zain said exactly three and Marcus said exactly four. Miss Spelling knew that the students who had not done their homework were not telling the truth but those who had done their homework were telling the truth.
How many of these students had done their homework the day before?
