From GMAT Paper Test 37,
A certain hotel has 1,400 single and 420 double rooms. Each room is cleaned by one person. If one person can clean a single room every 15 minutes and a double room every 20 minutes, how many cleaning persons are needed to clean all of the rooms if each person works for exactly 7 hours?
A) 65
B) 70
C) 80
D) 90
E) 265
Here's how I solved the question:
x = no. of cleaning persons to work on all of the rooms
[x][(1/0.25)(7) + (1/0.33)(7)] = 1,400 + 420
x = 37.14
Clearly, I didn't answer correctly since my answer isn't in any of the choices. Can someone show me how to solve this problem? Please show and explain using the rate/time formula, so I can see where I went wrong in the equation.
A certain hotel has 1,400 single and 420 double rooms. Each room is cleaned by one person. If one person can clean a single room every 15 minutes and a double room every 20 minutes, how many cleaning persons are needed to clean all of the rooms if each person works for exactly 7 hours?
A) 65
B) 70
C) 80
D) 90
E) 265
Here's how I solved the question:
x = no. of cleaning persons to work on all of the rooms
[x][(1/0.25)(7) + (1/0.33)(7)] = 1,400 + 420
x = 37.14
Clearly, I didn't answer correctly since my answer isn't in any of the choices. Can someone show me how to solve this problem? Please show and explain using the rate/time formula, so I can see where I went wrong in the equation.
