Part A:
The range is the difference between the highest and lowest values:
Highest value = 78
Lowest value = 40
Range = 78-40 = 38
Part B:
The interquartile range is the difference between Q1 and Q3.
Q1 is the middle value of the lower half and Q3 is the middle value of the upper half.
There are 11 total numbers, 40 , 64, 66, 67,67,68,69,70, 71, 72, 78
The median would be the middle value, 68, so the lower half would be the 5 numbers below 68: 40 , 64, 66, 67,67.
The middle value of those numbers would be 66
The upper half are the 5 numbers above 68: 69,70, 71, 72, 78.
The middle value of those numbers is 71
The interquartile range would be 71 - 66 = 5
Part C:
The interquartile range is the better measure.