[求助]2道Prep数学题解题思路 PS1 33, DS1 147

33.   4484-!-item-!-187;#058&004004

If x^4 + y^4 = 100, then the greatest possible value of x is between

(A) 0 and 3

(B) 3 and 6

(C) 6 and 9

(D) 9 and 12

(E) 12 and 15

Key: B

147.
                14800-!-item-!-187;#058&010134

Each employee on a certain task force is either a manager or a director.  What percent of the employees on the task force are directors?

(1) The average (arithmetic mean) salary of the managers on the task force is $5,000 less than the average salary of all employees on the task force.

(2) The average (arithmetic mean) salary of the directors on the task force is $15,000 greater than the average salary of all employees on the task force.

Key: C

Thank you in advance!