Video Transcript
The line plot shows the number of people who subscribed to an online course last June. The deadline for subscription was the 20th of June. How would the mode of the subscription dates be affected if the administration office forgot to record one person who subscribed on the 14th? Option (A) the mode would remain unchanged at the 10th. Option (B) the mode would remain unchanged at the 13th. Option (C) the mode would change from the 11th to be the 13th. Option (D) the mode would change from the 13th to be the 11th. Or is it option (E) the mode would change from no mode to the 14th?
In this question, we are given a line plot of the number of subscriptions of an online course last June. We are asked to use this line plot to determine how the mode of the subscription dates would change if there was a missing entry on the 14th.
To answer this question, we can start by noting that the deadline for subscriptions to the course is the 20th of June. We can also see that the line graph stops at the 20th, so there are no invalid subscriptions recorded. Since we want to compare the mode before and after the addition of the missing subscription, we can start by recalling that the mode of a data set is the element that appears most often in the data set. It is also worth recalling that there can be multiple modes, if there are multiple elements that appear equally the most often, or no mode, if all the elements appear equally often.
In a line plot, we know that each marking represents an element. For instance, we can see that there are two crosses in the diagram over day 10, this means that there were two subscriptions on the 10th. We can find the amount of subscriptions on each day by counting the number of crosses above the day’s number. We have zero subscriptions on the 11th, two subscriptions on the 12th, five subscriptions on the 13th, one subscription on the 14th, three subscriptions on the 15th, one subscription on the 16th, one subscription on the 17th, two subscriptions on the 18th, four subscriptions on the 19th, and two subscriptions on the 20th.
The mode of this data set is the day with the most number of subscriptions. We can see that this is the 13th. However, remember that the administration office forgot to record one person who subscribed on the 14th. We want to see how this error affects the mode. To do this, we can add an extra subscription on the 14th onto the line plot and update the number of subscriptions on the 14th to be one higher at two. We can then see that this is still lower than the number of subscriptions on the 13th. So the mode remains unchanged at the 13th.
Hence, the answer is option (B). The mode would remain unchanged at the 13th.
