5 A school principal wants to buy some book cases for the school library. She can choose between two types of book case. Type A costs $10 and it requires 0.6 m² of floor space
and holds 0.8 m' of books. Type B costs $20 and it requires 0.8 m² of floor space and
holds 1.2 m' of books. The maximum floor space available is 7.2 m² and the budget is
$140 (but the school would prefer to spend less). What number and type of book cases
should the principal buy to get the largest possible storage space for books?

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