Test 19 corrections

[yongcheng3315]

Test 19 corrections


(1)

Question 8:  It takes Alex 15 minutes to catch Betsy the first time and to run a total of 16 rounds more..."  means

Alex uses 15 minutes to catch Betsy the first time. When he catches Betsy the first time, Betsy runs x rounds and he runs (16 + x) rounds.


(2)

Test 19 #5
Should read AC = m
D is not labeled on diagram

[yongcheng3315]

#8 Solution:

Method 1:

Let d be the circumference of the circle and x be the number of rounds Betsy runs:

 (25/60)[(16+x)d/15 + xd/15] = d

Solve for x: x = 10.

Method 2:

Let Va and Vb be the speeds of Alex and Betsy, respectively.

(25/60)(Va + Vb) = d    (1)
15(Va - Vb) = 16d        (2)

Solve for Va/Vb.

Then Va/Vb = (16+x)/x.

x = 10.