for the data given below find the a. mean b. median c. mode d quartiles e.range f. variance g. standard deviation h. coefficient of variation i....

for the data given below find the

a. mean

b. median

c. mode

d quartiles

e.range

f. variance

g. standard deviation

h. coefficient of variation

i. interquartile range

j .a generalization of the skewness using the histogram with 5 classes

45 55 60 65 65 65 68 70

75 75 80 85 90 95 120

2. Using Z-tables answer the following questions. The population mean is 73 and the population standard deviation is 5.

a. What are the z-values for the following intervals?

b. What are the probabilities that an item selected at random will fall in the interval?

i. 53 < x < 9

ii. x < 65

iii. 78 < x 

3. A company manufactures watches. The watches are known from past observations to have an average life of 28 months and a standard deviation of watch lifetimes of 5 months. The distribution of lifetimes of the watches is normal. If the company does not want to make refunds on more than 12% of the watches it makes, how long should the guarantee period be (to the nearest month)?