As cars passed a checkpoint, the following speeds were clocked and recorded.

Speed (mph): 55 62 61 54 68 72 59 61 70
what's the range? , 1st quartile and 3rd quartile? please.
i know the mean is 62 and themin is 54 and the max is 72 and the 2nd quartile is 61

put them in ascending order.

54/55/59/61/ 61/ 62/ 68/70/72
range 54 to 72
I dont agree with your numbers.
http://www.mathsisfun.com/definitions/quartiles.html

so the range is 54 to 72

the min is 54
the max is 72
1quartile is 55?
2nd is 61
3rd is 70?
did i do good or?

To find the range, first, we need to sort the speeds in ascending order:

54 55 59 61 61 62 68 70 72

The range is then calculated as the difference between the maximum and minimum values:

Range = Maximum Value - Minimum Value
Range = 72 - 54
Range = 18 mph

To find the quartiles, we can use the following steps:

Step 1: Arrange the data in ascending order (already done)

Step 2: Find the median (2nd quartile)
The median is the middle value in the data set when it is arranged in ascending order. Since we have 9 data points, the median is the value at the (9+1)/2 = 5th position.

Median = 61 mph

Step 3: Find the lower quartile (1st quartile)
The lower quartile is the median of the lower half of the data set. In this case, since we have an odd number of data points, the lower half consists of the first four data points.

Lower Quartile = Median of the lower half
Lower Quartile = (55 + 59) / 2
Lower Quartile = 57 mph

Step 4: Find the upper quartile (3rd quartile)
The upper quartile is the median of the upper half of the data set. Using the same logic as above, the upper quartile consists of the last four data points.

Upper Quartile = Median of the upper half
Upper Quartile = (68 + 70) / 2
Upper Quartile = 69 mph

Therefore, the range is 18 mph, the 1st quartile is 57 mph, and the 3rd quartile is 69 mph.