Đề thi Olympic Tiếng Anh lớp 9 vòng 21 năm 2013 - 2014

Pipe A can fill a tank in 8 hours. When both pipe A and pipe B are used, the tank is filled in 5 hours. How long, in hours, would it take pipe B alone to fill the tank?

Jack and Jill sat at the ends of an 18-foot long seesaw where the fulcrum was placed in the middle of the board. By placing a 20-pound weight 3 feet in front of Jill, they were in bal-ance. If Jack weighs 140 pounds, which equation could be used to determine Jill's weight (x) in pounds?

When the expression above is simplified, the numerator is:

Solve for t in the expression above.

What is the value of c if x² + 7x + c is a perfect square?

The figure shows the graph of y = x² – 2x – 3. The expression x² – 2x – 3 is less than zero when:

The vertex of the parabola represented by y = x2 + 8x + 13 is in which quadrant?

The shaded region above is determined by which pair of inequalities?

Which of the following is an equation for line m?

Two planes intersect at line AB. Each plane contains a line that does not intersect AB. Which of the following terms describes the relationship between these two lines?