Use the already filled slots in the table to calculate the values in other slots. Remember that the last row and column represents the totals.
Gender
Have Siblings?
Boys
Girls
Total
Yes
20
25
45
No
15
10
25
Total
35
35
70
Practice makes perfect
We know that we asked 70 of our classmates if they have any siblings. To complete the two-way frequency table showing the results of the survey, we need to recognize that the last row and the last column show totals.
Gender
Have Siblings?
Boys
Girls
Total
Yes
25
45
No
15
Total
35
70
From the table above, we know that of the 45 students with siblings, 25 are girls. Also, of the 70 students surveyed, 35 are girls. With this information, we can find the number of boys who have siblings and the number of boys in total.
Boys With Siblings:& 45- 25= 20
Boys Total:& 70- 35= 35
Let's write the given and the newly obtained information in our table.
Gender
Have Siblings?
Boys
Girls
Total
Yes
20
25
45
No
15
Total
35
35
70
To complete the table, notice that of the 35 girls surveyed, 25 have siblings. Also, of the 70 students surveyed, 45 have siblings. With this information, we can find the number of girls who do not have siblings and the number of students who do not have siblings.
Girls Without Siblings:& 35- 25=10
Students Without Siblings:& 70- 45=25
With this information, we can finally complete our table!
