The data sets below include four random samples of pulse rates, in beats per minute. Each sample includes the pulse rates for 7 individuals. Use the range rule of thumb to find an estimate for the standard deviation, then determine which sample has the smallest amount of variation. Sample 1 64,78,54,102,76,86,56 Sample 2 100,90,70,70,78,70,94 Sample 3 70,66,50,72,66,64,54 Sample 4 78,36,102,68,66,56,70