This is the 2013 Grade 8 Math Challenge Elimination Level Questions with Answers – Part 2. Questions in the previous years can be accessed on the Past Tests page and all questions can be found in the All Posts page.
26.) What should be subtracted from to get
27.) If , what is
28.) A storage battery discharges at a rate which is proportional to the storage. If the charge is reduced by 25% of its original value at the end of 3 days, how long will it take to reduce the charge to 10% of its original charge?
29.) If r and s are the roots of the equation , what is
30.) The value of C varies directly with x and the square of y and inversely with the cube of z. If each x, y and z are to be increased by 50%, what would be the effect on the value of C?
31.) If the sum of the reciprocals of the roots of the equation is what is k?
32.) A long wire is cut into three smaller pieces in the ratio of 7 : 3 : 2. If the shortest piece 16 cm, what is the area of the largest rectangle that can be created using the longest piece?
33.) Find the value of x in the equation
34.) Find the largest integer n such that 1 + 2 + 3 + · · · + n < 500.
35.) A boat takes 2/3 as much time to travel downstream as to return. If the rate of the river’s current is 8 kph, what is the rate of the boat in still water?
36.) If what is
37.) Find the value(s) of x so that x, 2x + 7 and 10x − 7 will form a geometric sequence.
38.) If , what is x? (Note: Ten terms of )
39.) In let D be the point on side BC such that AB = AC = BD. If what is
40.) Let be an arithmetic sequence. If and , what is
41.) What is the fourth root of
42.) The operation is defined by What is
43.) Triangle ABC is isosceles with AB = AC. Let D be the foot of the altitude from A on BC, and let E be the point on side AC such that DE bisects If what is
44.) Let be a non-constant arithmetic sequence. If and form a geometric sequence, what is the common ratio of this geometric sequence?
45.) What is the greatest integer less than or equal to
46.) If and , what is
47.) If , find
49.) Solve for x:
50.) If find the value of
28.) 10.8 days or
30.) no effect.
32.) 196 cm²
35.) 40 kph
37.) 7 and
View Part 1 here: 2013 Grade 8 Math Challenge Elimination Level Questions with Answers – Part 1