Answer:
12 hours
Step-by-step explanation:
Let's call the Jennifer's speed J, and the Krystal's speed K.
If Jennifer works alone, she can do the job in 6 hours, so:
J*6 = 1000
J = 1000/6 = 500/3
If Jennifer and Krystal work together, they can do the job in 4 hours, so:
(J+K)*4 = 1000
J+K = 250
Using the value of J, we can find K:
500/3 + K = 250
K = 250 - 500/3 = 250/3
Now, to find the time that Krystal would take if she works alone:
K * time = 1000
250/3 * time = 1000
time = 1000/ (250/3) = 1000*3/250 = 12 hours
