Final answer:
The cumulative frequency of observation b is 55%, and the cumulative frequency of c would be 100%, given a dataset where observations a, b, and c sum to a 100% relative frequency and a and c are 35% and 45% respectively.
Step-by-step explanation:
The question is asking to find the cumulative frequency of observations b and c given a dataset with three distinct observations and their relative frequencies. Since the relative frequencies of a and c are given as 35% and 45% respectively, we can calculate the relative frequency of b as the remaining percentage which would be 100% - 35% - 45% = 20%.
The cumulative frequency of b and c can be found by first calculating the cumulative relative frequencies of a and c. The relative frequency of a is 35%, which can be written as 0.35. The relative frequency of c is 45%, or 0.45. To find the cumulative relative frequency of c, we add the relative frequencies of a and c: 0.35 + 0.45 = 0.8. Therefore, the cumulative frequency of b and c is 0.8.
To find the cumulative frequency for b and c, we need to add the relative frequency of a (35%) to the relative frequency of b, giving us 35% + 20% = 55%. The cumulative frequency for c would then be the sum of the relative frequencies of a, b, and c which is 35% + 20% + 45% = 100%.