The function models the average typing speed S , in words per minute, of a student who has been typing for t months. Use a graph of S to determine how long, to the nearest tenth of a month, it will take the student to achieve an average typing speed of 68 words per minute.
A)5.6 months
B)7.5 months
C)1.8 months
D)5.2 months
E)1.9 months

Question

The function  models the average typing speed S , in words per minute, of a student who has been typing for t months. Use a graph of S to determine how long, to the nearest tenth of a month, it will take the student to achieve an average typing speed of 68 words per minute.
A)5.6 months 
B)7.5 months 
C)1.8 months 
D)5.2 months 
E)1.9 months

Quizplus · Accepted Answer

To find when the student will achieve an average typing speed of 68 words per minute, we need to solve for t in the equation S= 11ebfdc1_ec32_f5b1_abe3_a3e405b42d5b_TBX8727_11 = 68. This can be done graphically by plotting the function on a graphing calculator or by hand. 
From the graph, we see that the function intersects the line y = 68 at approximately t = 7.5 months. Therefore, the answer is B) 7.5 months.

The Function Models the Average Typing Speed S