Measures of location and spreadEdexcel A-Level Maths: Mind map

Exam questions on Measures of location and spread

1. The delivery times, $x$ minutes, of 10 parcels have $\sum x=240$ and $\sum x^2=6100$.
   Calculate the standard deviation of the delivery times.2 marks
2. A sample of 8 masses, $x$ grams, is coded using $y=\frac{x-400}{10}$. The coded data have $\sum y=24$ and $\sum y^2=130$.
   A second sample is formed by adding 5 g to every mass in this sample. State the effect on (i) the mean and (ii) the standard deviation.2 marks
3. A clinic records the waiting times of 50 patients, in minutes: 4 patients waited from 0 up to 10, 12 from 10 up to 20, 20 from 20 up to 30 and 14 from 30 up to 50.
   Estimate the mean waiting time.3 marks