Sam’s garden has two taps. The first fills a 5-litre container in 20 seconds, while the second takes 30 seconds. At these rates, how many more litres per minute does the first tap deliver than the second?
Cinema seats form a rectangular array. Marry sits in the fifth row from the front and the sixth from the back. Tony sits in the tenth column from the left and the eleventh from the right. How many seats are there?
Sam must score at least 28 points in total on three tests to graduate from an extracurricular course. Each test score is a whole number from 0 to 10. He meets the requirement. How many different ordered triples of test scores are possible?
Some students attend an art-club meeting. After five girls leave, the boys number twice the remaining girls. Then 15 boys leave, and the girls number three times the remaining boys. How many girls attended initially?
Tom watched the seven games in the quarterfinals, semifinals and final of an elimination noughts-and-crosses tournament. He reports six results: Bella beat Anna; Gina beat Celine; Celine beat Donna; Celine beat Bella; Gina beat Holly; Emma beat Farah. What was the missing result?
Maria starts weaving on January 1 and makes 25 metres of cloth each day. At the end of each day she gives her sister one tenth of all the cloth she then has. On which date does the amount she keeps first exceed 100 metres?
Experts from the Czech Republic, Slovakia and Poland meet at a conference. There are eight Polish experts, and the Slovak group is largest. There are 13 women, half the number of men. Which statement must be true?
More than one third of the experts are women.
The Polish group makes up more than 25% of the attendees.
Two intersecting circles lie in an a×b rectangle, where a<b. Each circle is tangent to three sides of the rectangle, as shown. In general, what is the distance between their centres?
Bob and Tom race on a 300 m track. Bob gives Tom a 200 m head start. They start together and run at constant speeds, and Bob never passes Tom before the finish. At most how many times Tom’s speed can Bob’s speed be?