SOLUTION: working together, alice and betty can do a certain job in 4 1/3 days. but alice fell ill after 2 days of working and betty finished the job continuing to work alone in 6 3/4 more d

Algebra ->  Rate-of-work-word-problems -> SOLUTION: working together, alice and betty can do a certain job in 4 1/3 days. but alice fell ill after 2 days of working and betty finished the job continuing to work alone in 6 3/4 more d      Log On


   



Question 150509This question is from textbook
: working together, alice and betty can do a certain job in 4 1/3 days. but alice fell ill after 2 days of working and betty finished the job continuing to work alone in 6 3/4 more days. how long would it take each to do the job if each of them worked alone? This question is from textbook

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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working together, alice and betty can do a certain job in 4 1/3 days. but alice fell ill after 2 days of working and betty finished the job continuing to work alone in 6 3/4 more days. how long would it take each to do the job if each of them worked alone?
:
Let a = time required by Alice working alone
Let b = time required by Betty alone
Let the completed job = 1
:
equation when they both work 41%2F3 day
4.33%2Fa + 4.33%2Fb = 1
Multiply equation by 3 give us integers to work with
13%2Fa + 13%2Fb = 3
:
Equation when one got sick; (b worked a total of 2+6.75 = 8.75
2%2Fa + 8.75%2Fb = 1
Multiply equation by 6.5
13%2Fa + 56.875%2Fb = 6.5
:
Use elimination here:
13%2Fa + 56.875%2Fb = 6.5
13%2Fa + 13%2Fb = 3
-------------------------------subtraction eliminates a, find b
43.875%2Fb = 3.5
3.5b = 43.875
b = 43.75%2F3.5
b = 12.5357 days for Betty alone
:
Use 13%2Fa + 13%2Fb = 3, substitute for b and find a
13%2Fa + 13%2F12.5357 = 3
13%2Fa + 1.037 = 3
13%2Fa = 3 - 1.037
13%2Fa = 1.963
1.963a = 13
a = 13%2F1.963
a = 6.6225 days for Alice alone
;
:
To check solutions, use 2%2Fa + 8.75%2Fb = 1, substituting for a and b:
2%2F6.6225 + 8.75%2F12.5357 = 1
.302 + .698 = 1; confirms our solution