Diana

[gibran]

Yesterday Diana spent a total of 240 minutes attending a training class, responding to E-mails, and talking on the phone. If she did no two of these three activities at the same time, how much time did she spend talking on the phone?
(1) Yesterday the amount of time that Diana spent attending the training class was 90 percent of the amount of time that she spent responding to E-mails.
(2) Yesterday the amount of time that Diana spent attending the training class was 60 percent of the total amount of time that she spent responding to E-mails and talking on the phone.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient

Official Answer is C. Please help to explain.

[leanmeanprepforgmat]

A = time spent training
B = time spent emailing
C = time spend talking on phone

A+B+C=240, C=?

(1) A = 0.9*B
implies 0.9B + B + C = 240
can't solve for C since there are 2 variables and 1 equation
[insufficient alone]

(2) A = 0.6*(B+C)
implies 0.6B + 0.6C + C = 240
again 2 variables and 1 equation, so can't solve for C
[insufficient alone]

(1) + (2)
you have 2 equations for B and C
1.9B + C = 240
0.6B + 1.6C = 240
you can solve for C

Implies both statements together are sufficient

Answer is (C)

[tarkumar]

IMO C

T = time spent training
E = time spent emailing
P = time spend talking on phone
T+P+E = 240 ....equation 1

1) T = 0.9*E ...insuff three variables two equaltions.
2) T = 0.6 * (E+P) T can be found using this and equation 1 but P can't be obtained..Isuff

Together.. T can be obtianed using statement 2.
E can be obtained using statement 1 and then P can be found using statement 2.

Hope this helps

[mannu08]

yes ans is C

[Widy]

Great explaination Leanmeanprepforgmat...thanks!