In a grouped frequency distribution one interval is listed as 50-54. assuming that the scores are measuring a continuous variable, what are the real limits of this interval
a. 49.5 and 54.5
b. 50 and 54
c. 50.5 and 54.5
d. 50.5 and 53.5

a. 49.5 and 54.5

Step-by-step explanation:

Class interval is a range of a value that is used to group data into equal size for easy analysis and representation of the data. It is applicable in the divisions of a histogram or bar chart into classes.  Examples of class interval are 50-54, 55-59, 60-64, 65-69, 70-74 etc.

Class limit is the minimum and maximum value the class interval may contain. The minimum value is called the lower class limit and the maximum value is called the upper class limit. For class interval 50-54, the lower class limit is 50 and the upper class limit is 54.

Class boundaries are the numbers used to separate classes. It is the real limits of a class. For non-overlapping classes, the lower class boundary of each class is calculated by subtracting 0.5 from the lower class limit. The upper class boundary of each class is calculated by adding 0.5 to the upper class limit. Example: For class interval 50-54, the lower class boundary is 49.5 and the upper class class boundary is 54.5

Considering the question given, to get the real limits of the interval 50-54, 0.5 is subtracted from the lower class limit to give 49.5. Also, 0.5 is added to the upper class limit to give 54.5.

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.

you probably already have the answer but anyways it's b. 15.0

step-by-step explanation: