mjg2110 wrote:
If Company M ordered a total of 50 computers and printers and Company N ordered a total of 60 computers and printers, how many printers did company M order?
(1) Company M and Company N ordered the same number of computers
(2) Company N ordered 10 more printers than Company M
Sometimes, algebra makes a problem easier.
Sometimes, algebra makes a problem HARDER.
(1) Company M and Company N ordered the same number of computers
Case 1: Each company orders 10 computers
In this case:
M orders 40 printers, for a total of 50 computers and printers
N orders 50 printers, for a total of 60 computers and printers
Case 2: Each company orders 20 computers
In this case:
M orders 30 printers, for a total of 50 computers and printers
N orders 40 printers, for a total of 60 computers and printers
Since the number of printers for M can be different values, INSUFFICIENT.
The two cases above also satisfy the condition in Statement 2 that N orders 10 more printers than M.
Implication:
Even when the statements are combined, the number of printers for M can be different values, with the result that the two statements combined are INSUFFICIENT.
A useful rule of thumb:
If you suspect that a statement is SUFFICIENT, then algebra might be the best approach.
Why?
Because sufficiency suggests that an equation can be created to solve for the desired value.
If you suspect that a statement is INSUFFICIENT, then testing cases might be more efficient.
Why?
Because insufficiency suggests that an equation CANNOT be created to solve for the desired value.