Exam-Style Questions on Cumulative frequency
Problems on Cumulative frequency adapted from questions set in previous exams.
The table shows the test marks for 31 students.
|5 ≤ p < 15||2|
|15 ≤ p < 25||3|
|25 ≤ p < 35||4|
|35 ≤ p < 45||3|
|45 ≤ p < 55||8|
|55 ≤ p < 65||8|
|65 ≤ p < 75||2|
|75 ≤ p < 85||1|
Marco drew this cumulative frequency graph using the data.
Make three criticisms of Marco’s graph.
The weights in grams of 98 mice are shown in the cumulative frequency diagram. The heaviest mouse weighted 160g.
(a) Write down the median weight of the mice.
(b) Find the percentage of mice that weigh 70 grams or less.
The same data is presented in the following table.
|Weights w grams||0 < w ≤ 40||40 < w ≤ 80||80 < w ≤ 120||120 < w ≤ 160|
(c) Find the value of p.
(d) Find the value of q.
(e) Use the values from the table to estimate the mean and standard deviation of the weights.
A second batch of mice are normally distributed with the same mean and standard deviation as those of the first group mentioned above.
(f) Find the percentage of the second batch of mice that weigh 70 grams or less.
(g) A sample of five mice is chosen at random from the second batch. Find the probability that at most three mice weigh 70 grams or less.