WAEC Past Questions and Answers - Page 3906

19,526.

If \(y \propto \frac{1}{\sqrt{x}}\) and x = 16 when y = 2, find x when y = 24

A.

\(\frac{1}{9}\)

B.

\(\frac{1}{6}\)

C.

\(\frac{1}{3}\)

D.

\(\frac{2}{3}\)

Correct answer is A

\(y \propto \frac{1}{\sqrt{x}}\)

\(y = \frac{k}{\sqrt{x}}\)

When x = 16, y = 2.

\(2 = \frac{k}{\sqrt{16}} \implies 2 = \frac{k}{4}\)

\(k = 8\)

\(y = \frac{8}{\sqrt{x}}\)

When y = 24,

\(24 = \frac{8}{\sqrt{x}}\)

\(\sqrt{x} = \frac{8}{24} = \frac{1}{3}\)

\(\therefore x = (\frac{1}{3})^2\)

\(x = \frac{1}{9}\)

19,527.

Use the following equations to answer the question below
I - Boiled saliva + starch → X
II - Fresh saliva + starch → Y

What substances do X and Y represent?

A.

X = Maltose and Y = Sugar

B.

X = Starch and Y = Maltose

C.

X = Sugar and Y = Starch

D.

X = Maltose and Y = Starch

Correct answer is B

No explanation has been provided for this answer.

19,528.

Subtract (-y + 3x + 5z) from (4y - x - 2z)

A.

5y - 4x - 7z

B.

3y + 2x + 3z

C.

-5y + 4x + 7z

D.

2x - 5y + 3z

Correct answer is A

(4y - x - 2z) - (-y + 3x + 5z)

= 4y + y - x - 3x - 2z - 5z

= 5y - 4x - 7z

19,529.

Enzymes can be inactivated by certain chemical substances in the body called

A.

catalysts

B.

inhibitors

C.

substrates

D.

activators

Correct answer is B

No explanation has been provided for this answer.

19,530.

The graph of the curve \(y = 2x^2 - 5x - 1\) and a straight line PQ were drawn to solve the equation \(2x^2 - 5x + 2 = 0\)
What is the equation of the straight line PQ?

A.

y = -1

B.

y = 1

C.

y = 3

D.

y = -3

Correct answer is D

Let the straight line PQ = y

2x\(^2\) - 5x - 1 - y = 2x\(^2\) - 5x + 2

y = 2x\(^2\) - 5x - 1 - 2x\(^2\) + 5x - 2 

y = -3