Question

Does singing to plants help them grow? You decide to test the effectiveness of your singing prowess on plant growth by singing to six different plants each day for 3 months (it would seem you have nothing better to do with your time). You start each plant with a seed and then count the number of leaves produced at the end of the 3 months. You data looks like this: 1, 2, 4, 5, 7, 11 1.

1. What scale of measurement was used by the researcher?
2. Calculate the mean, median, mode.
3. Calculate the range, variance and standard deviation for the data set using the formula for sample variance and SD.
4. Based on your sample, what is the number of leaves associated with +2SD?
5. What number of leaves are associated with 68% of the sample?​

Answer 1

The scale of measurement used by the researcher is interval scale as the data is continuous and there are equal intervals between the values.

Mean = (1+2+4+5+7+11)/6 = 5

Median = (4+5)/2 = 4.5

Mode = There is no mode in the data set as none of the numbers are repeated.

Range = maximum value - minimum value = 11 - 1 = 10

Sample Variance = ((1-5)^2 + (2-5)^2 + (4-5)^2 + (5-5)^2 + (7-5)^2 + (11-5)^2)/(6-1) = 14.67

Standard Deviation = sqrt(sample variance) = sqrt(14.67) = 3.83

Mean + 2SD = 5 + 2*3.83 = 12.66, rounded to the nearest integer = 13.

According to the Empirical Rule, 68% of the sample lies within 1 standard deviation of the mean. Therefore, we need to find the values that are 1 standard deviation away from the mean:

Lower limit = Mean - SD = 5 - 3.83 = 1.17, rounded to the nearest integer = 1.

Upper limit = Mean + SD = 5 + 3.83 = 8.83, rounded to the nearest integer = 9.

So the number of leaves associated with 68% of the sample is between 1 and 9.

Explanation: