How to Take This Test
25 questions in 15 minutes is about 36 seconds a question, the pace of the real Tier 1 Maths section. At that speed the short forms have to be ready: sum = average × count, change × count for anyone joining, leaving or being replaced, and the distances from the overall average when two groups are put together. Number series, cricket, wrong entries, groups and ages come in mixed order.
- Start a 15-minute timer and finish in one go, with your notes closed.
- A right answer gets +2, a wrong one −0.50, and a skipped one 0.
- A long overlapping-groups or age question can eat the time of three short ones. Leave it and come back at the end.
- Look at the explanations only when the time is up.
Your score. Score = 2 × (number right) − 0.5 × (number wrong), and the maximum is 50. So 19 right, 4 wrong and 2 skipped scores 38 − 2 = 36.
| Score out of 50 | What to do next |
|---|---|
| 40 or more | You are ready on averages. Do a PYQ Practice Set now and then so the methods stay quick. |
| 30 to 39.5 | The base is good. If your mistakes were mostly n versus n + 1 slips, redo the Change in Average quiz; if they were plain averages of two group averages, redo the Weighted Average and Combined Groups quiz. |
| 20 to 29.5 | You know the methods but they are slow. Go through Shortcuts & Speed Methods, mainly change × count and the see-saw, then Practice Sets 1 and 2, and take this test again in a few days. |
| Below 20 | Go back to the four topic sections, Average Basics and Averages of Numbers, Change in Average: Joining, Leaving, Replacement and Errors, Weighted Average and Combined Groups and Average Ages and Age Problems, before you try more timed tests. |
The tag on each question tells you where to look: number series, consecutive numbers, overlapping groups and days are in Average Basics and Averages of Numbers; one added or removed, replacement, wrong entries, cricket and target marks in Change in Average; combined averages, group sizes, weighted percentages and salaries in Weighted Average and Combined Groups; and anything about ages in Average Ages and Age Problems.
More than 3 wrong answers usually means you were rushing, so slow down a little next time. On guessing: with +2 and −0.50, even a blind guess between four options is very slightly in your favour on average, and once you can rule out one option a guess is clearly worth taking (Chapter 0 works out the numbers).