Answer:
a) 40<x<50
b)30<x<40
Step-by-step explanation:
Modal class means that interval with the highest frequency, which in this case is the time spent between 40 and 50 min.
The median is just the middle value of a set. So to find the median, just add all the frequencies and divide by 2.
18+14+3+16+21+7 = 79
since it is odd and we get 39.5 when dividing by 2, you take the unrounded and rounded number, so 39 and 40 are the median. That means you take the class where the 39th and 40th frequency is located, which is at 30 and 40 minutes.
Hope that answers your question