newspaper delivery. Samantha can deliver papers three times as fast as her sister, Elizabeth if they work together, it takes them 1 hour. how long would it take

Question

How long would it take each to deliver the papers alone?

Answer 1

E = 3S S=E/3

1/S + 1/E = 1/1

1/(E/3) + 1/E = 1

3/E + 1/E = 1

3 + 1 = E = 4 hours to do it alone for Elizabeth

S= 4/3 hours = 1 hour and 20 minutes to do it alone for Samantha

if each worked at the same speed they both do it alone in 2 hours each

1/2 + 1/2 = 1 hour

1/3 + 1/1.5 = 1 hour if S worked twice as fast as E

1/4 + 1/(4/3) = 1 hour if S works 3 times as fast as E

Elizabeth takes 4 hours alone

Samantha takes 4/3 = 1 hour and 20 minutes alone