Question

question 29
180 people are asked how many siblings they have?
the (incomplete) results are shown below (please use 4 decimal places when apply):

of siblings frequency relative frequency cumulative frequency

0 40 0.2222 40
1 37 0.2056
2 0.2111 115
3 33 0.1833 148
4 32 180
complete the table and determine what percent of the people have exactly three sibling(s)? %

Explanation:

Step1: Find Cumulative Frequency for 1 sibling

Cumulative Frequency for a category is the sum of frequencies up to that category. For 1 sibling, it's Frequency of 0 + Frequency of 1.
$40 + 37 = 77$

Step2: Find Frequency for 2 siblings

Cumulative Frequency for 2 is 115, and Cumulative Frequency for 1 is 77. So Frequency of 2 is $115 - 77 = 38$ (we can also verify with Relative Frequency: $180\times0.2111\approx38$)

Step3: Find Relative Frequency for 4 siblings

Relative Frequency is Frequency divided by total number of people (180). So for 4 siblings: $\frac{32}{180}\approx0.1778$

Step4: Find percentage of people with exactly 3 siblings

Relative Frequency for 3 siblings is 0.1833. To convert to percentage, multiply by 100.
$0.1833\times100 = 18.33\%$ (or using Frequency: $\frac{33}{180}\times100 = 18.3333\approx18.33\%$)

Answer:

Cumulative Frequency for 1: 77
Frequency for 2: 38
Relative Frequency for 4: 0.1778
Percentage with 3 siblings: 18.33% (or 18.3333% if more decimals)