Here are four questions from a test comprising "27 straightforward maths questions" which were presented to 155 primary school teachers for the Channel 4 documentary series Dispatches. The number in brackets at the end of each question is the percentage of the tested teachers who answered the question correctly.
Q1: The mean height of a group of four people is 2m. One more person joins the group and then the mean height is 1·9m. What is the height of the new person? (14)
Q2: ABCDE is a pentagon. Name all its diagonals. (25)
Q3: Assume 5 miles = 8 km. If I travel at 40mph, how long will I take to cover 32km? (32)
Q4: 112 x 22 = 2,464. What is the value of 1.12 x 2.2? (54)
See here for the story in the Guardian complete with the answers and here for the Despatches web page on the topic. Note that the second episode will be shown tonight at 8.00 pm.
The source for this entry is the redoutable Frank Chalk.