1.The following table gives the cumulative frequency distribution of the commuting time (in minutes) from home to work for a sample of 400 persons selected from a city.

Time (minutes)f

0 to less than 1060

0 to less than 20149

0 to less than 30224

0 to less than 40287

0 to less than 50357

0 to less than 60400

The sample size is:

The percentage of persons who commute for less than 30 minutes, rounded to two decimal places, is:

%

The cumulative relative frequency of the fourth class, rounded to four decimal places, is:

The percentage of persons who commute for 40 or more minutes, rounded to two decimal places, is:

%

The percentage of persons who commute for less than 50 minutes, rounded to two decimal places, is:

%

The number of persons who commute for 20 or more minutes is:

2.The temperatures (in degrees Fahrenheit) observed during seven days of summer in Los Angeles are:

78996891947585

The range of these temperatures is:

The variance of these temperatures, rounded to three decimals, is:

The standard deviation, rounded to three decimals, of these temperatures is:

3.For the probability distribution of a discrete random variablex, the sum of the probabilities of all values ofxmust be:

equal to zero

in the range zero to 1

equal to 1

equal to 0.5