To find the expected number of times Song should pull a purple marble in 25 more trials, we first need to determine the probability of pulling a purple marble from the initial results.
- Calculate the total number of trials:
Total trials = Frequency of Blue + Frequency of Green + Frequency of Purple + Frequency of Red + Frequency of Yellow
Total trials = 22 + 19 + 20 + 18 + 21 = 100
- Calculate the probability of pulling a purple marble:
Probability of Purple = Frequency of Purple / Total trials
Probability of Purple = 20 / 100 = 0.2
- Use the probability to calculate the expected number of times Song should pull a purple marble in 25 more trials:
Expected number of Purple = Probability of Purple * Number of additional trials
Expected number of Purple = 0.2 * 25 = 5
Thus, Song should expect to pull a purple marble 5 times.