1 Different types of watches lose accuracy at different rates, as shown in the table below. Seconds gained lost per 24 hours
Type of watch
Worst Typical Best
Vintage mechanical 360 215 15
Modern mechanical
t10
Modern quartz
+2 +1
10.1
Marcello has one watch of each type. He synchronises them so that they all show exactly the
same time
What is the biggest difference there could be between the times shown on two of the watches
after 24 hours?
A 10 seconds
B 20 seconds
C 50 seconds
D
70 seconds
No

Each of the following data sets has a mean of x = 10. (i) 8 9 10 11 12 (ii) 7 9 10 11 13 (iii) 7 8 10 12 13 (a) without doing any computations, order the data sets according to increasing value of standard deviations. (i), (iii), (ii) (ii), (i), (iii) (iii), (i), (ii) (iii), (ii), (i) (i), (ii), (iii) (ii), (iii), (i) (b) why do you expect the difference in standard deviations between data sets (i) and (ii) to be greater than the difference in standard deviations between data sets (ii) and (iii)? hint: consider how much the data in the respective sets differ from the mean. the data change between data sets (i) and (ii) increased the squared difference îł(x - x)2 by more than data sets (ii) and (iii). the data change between data sets (ii) and (iii) increased the squared difference îł(x - x)2 by more than data sets (i) and (ii). the data change between data sets (i) and (ii) decreased the squared difference îł(x - x)2 by more than data sets (ii) and (iii). none of the above