Question

the average number of hours a user spent each month on a particular site increased from 15 in 2018 to 17.5 in 2020, then decreased to 16 in 2021. use a graph that displays the average monthly hours spent on the site as a function of time to estimate the monthly usage for 2019 and for 2023. choose the correct graph. let the horizontal axis, t, represent the year and t... the average number of hours a user spent each month. the average number of hours a user spent each month for the year 2019 is dropdown with 13, 16.25, 13.75, 17.5 (graphs a, b, c, d with horizontal axis 2016–2025, vertical axis h (hours) with ranges 12–18 (a, b, d) or 2–8 (c) shown)

Explanation:

Step1: Identify the trend and key points

We know the usage: 15 hours in 2018, 17.5 hours in 2020, and 16 hours in 2021. We need to find the value in 2019. Since it's an increase from 2018 to 2020, we can assume a linear increase (or a reasonable trend) between 2018 and 2020. The time between 2018 and 2020 is 2 years. So the increase from 2018 to 2020 is \(17.5 - 15=2.5\) hours over 2 years. So per year increase is \(\frac{2.5}{2} = 1.25\) hours per year.

Step2: Calculate 2019 usage

In 2019, which is 1 year after 2018, the usage would be \(15 + 1.25=16.25\) hours? Wait, no, wait. Wait, maybe the graph is a line graph with points. Wait, let's re - evaluate. Wait, the problem says "the average number of hours a user spent each month on a particular site increased from 15 in 2018 to 17.5 in 2020, then decreased to 16 in 2021". So from 2018 (15) to 2020 (17.5), that's a linear increase? So the mid - point between 2018 and 2020 is 2019. The formula for the mid - point (average) of two numbers \(a\) and \(b\) is \(\frac{a + b}{2}\). Here, \(a = 15\) (2018) and \(b=17.5\) (2020). So \(\frac{15 + 17.5}{2}=\frac{32.5}{2}=16.25\).

Answer:

16.25