Here are the questions, answers and explanations. I have also included the percentage of children who got it right and the percentage of Guardian readers who did. In one question children did better than Guardian readers (although this was the one with the image that stretched) and in two others the scores were equal. Well done all round, anyway.
I hope you enjoyed the mental work out – Ill be back with another puzzle in two weeks.
1. What is the value of 1/25 + 0.25? Answer: 0.29
1/25 = 4/100 = 0.04.
So 1/25 + 0.25 = 0.04 + 0.25 = 0.29
Children: 52 per cent correct (3 per cent did not answer).
Guardian readers: 81 per cent correct.
2. Gill is now 28 years old and is a teacher of Mathematics at a school which has 600 pupils. There are 30 more girls than boys at the school.
How many girls are at Gills school? Answer: 315.
Let there be g girls in Gills school. Then there are (g 30) boys at the school.
So g + g 30 = 600 . Therefore 2g = 630 , that is g = 315.
Children: 52 per cent (2 per cent did not answer).
Guardian readers: 81 per cent.
3. One of the three symbols +, , x is inserted somewhere between the digits of 2016 to give a new number. For example, 20 16 gives 4.
How many of the following four numbers can be obtained in this way?
36, 195, 207, 320
All four numbers may be obtained: 20 + 16 = 36; 201 6 = 195; 201 + 6 = 207; 20 x 16 = 320.
Children: 39 per cent (3 per cent did not answer).
Guardian readers: 62 per cent.
4. A square is folded exactly in half and then in half again. Which of the following could not be the resulting shape? Answer: D