Answer:
85 wpm
Step-by-step explanation:
From the scatter plot, we can see the following;
At 20 hours, average typing speed = 34 wpm
At 30 hours, the average typing speed = 40 wpm
At 40 hours, the average typing speed = 51 wpm
At 50 hours, the average typing speed = 65 wpm
Average differences = ((40 - 34) + (51 - 40) + (65 - 51))/3 = 10.3
Approximating to a whole number = 10
Now, we can approximate that at 60 hours, average typing speed = 65 + 10 = 75 wpm
At 70 hours, the average typing speed = 75 + 10 = 85 wpm
