Bunuel
Official Solution:
If Jim saved a total of $90 in 3 weeks, how much did he save in week 2?
Let \(s_1\), \(s_2\), and \(s_3\) represent the amounts Jim saved in the first, second, and third weeks, respectively.
(1) Jim's average (arithmetic mean) savings per week for the first two weeks was $22.5.
From this, we infer: \(s_1 + s_2 = 2*22.5 = 45\). However, this does not provide the specific value of \(s_2\). Hence, not sufficient.
(2) In the first week, Jim saved half of what he saved in week 2 and one-third of what he saved in week 3.
The above implies that \(2 *s_1 = s_2\) and \(3*s_1 = s_3\). Given that \(s_1 + s_2 + s_3 = 90\), we get \(s_1 + 2 *s_1 + 3*s_1 = 90\). Solving this, gives \(s_1 = 15\), and therefore, \(s_2 = 2*s_1 = 30\). This is sufficient.
Answer: B
I don't agree with the explanation because in statement two it says
"In the first week, Jim saved half of what he saved in week 2 and one-third of what he saved in week 3" ; which implies s1 = s2/2 + s3/3 . Hence since we already know that s1+s2+s3=90 ; we get the simplified equation as s2/2 + s3/3 + s2 + s3 = 90 => 3*s2/2 + 4*s3/3 = 90 ; two unknown so statement two along isn't sufficient.So hence I feel the answer should be "BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient". So , the correct answer is option C.You are misinterpreting the statement. "And" does not imply a sum; it indicates two separate conditions: s2 = 2s1 and s3 = 3s1. This allows direct solving, making statement 2 sufficient. Review the solution carefully. The correct answer is B, not C.