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WAEC Further Mathematics Past Questions & Answers - Page 2

6.

The probabilities that Atta and Tunde will hit a target in a shooting contest are 16 and 19 respectively. Find the probability that only one of them will hit the target.

A.

154

B.

4154

C.

2027

D.

1354

Correct answer is D

P(A)=16,P(T)=19

Probability that only one of them will hit the target = P(A)×P(ˉT)+P(ˉA)×P(T)

Where P(ˉT) is the probability that Tunde will not hit the target and P(ˉA) is the probability that Atta will not hit the target

P(ˉT)=119=89

P(ˉA)=116=56

Pr(only one) =(16×89)+(56×19)=427+554

pr (only one) = \frac{13}{54}

7.

A function f is defined by f :x→\frac{x + 2}{x - 3},x ≠ 3.Find the inverse of f .

A.

\frac{x + 3}{x - 2},x ≠ 2

B.

\frac{x - 3}{x + 2},x ≠ -2

C.

\frac{3x - 2}{x+1},x ≠ -1

D.

\frac{3x + 2}{x - 1},x ≠ 1

Correct answer is D

f :x→\frac{x + 2}{x - 3},x ≠ 3, f = ?

Let f :x=y

y=\frac{x + 2}{x - 3}

=x+2=y(x-3)

=x-xy=-3y-2

=x(1-y)=-3y-2

=x=\frac{-3y - 2}{1 - y}=\frac{-(3y + 2)}{- (y - 1)}

=x=\frac{3y + 2}{y - 1}

∴f ^{-1} : x=\frac{3x + 2}{x - 1},x ≠ 1

8.

If X and Y are two independent events such that P (X) = \frac{1}{8} and P (X ⋃ Y) = \frac{5}{8}, find P (Y).

A.

\frac{1}{6}

B.

\frac{4}{7}

C.

\frac{4}{21}

D.

\frac{3}{7}

Correct answer is B

P(X⋃Y)=\frac{5}{8}

P(X⋂Y)=P(X)\times P(Y)

Since X and Y are independent events, the probability of their union (X ⋃ Y) can be calculated as:

P(X⋃Y)=P(X)+P(Y)-P(X⋂Y)

=\frac{5}{8}=\frac{1}{8}+P(Y)-\frac{1}{8}\times P(Y)

=\frac{5}{8}-\frac{1}{8}=P(Y)-\frac{1}{8}\times P(Y)

=\frac{1}{2}=P(Y)(1-\frac{1}{8})

=\frac{1}{2}=P(Y)(\frac{7}{8})

=P(Y)=\frac{1}{2}÷\frac{7}{8}

∴P(Y)=\frac{1}{2}x\frac{8}{7}=\frac{4}{7}

9.

Given that y^2 + xy = 5,find \frac{dy}{dx}

A.

\frac{y}{2y + x}

B.

\frac{-y}{2y + x}

C.

\frac{-y}{2y - x}

D.

\frac{y}{2y + x}

Correct answer is B

y^2 + xy = 5

By implicit differentiation

=2y\frac{dy}{dx}+y+x\frac{dy}{dx}=0

=2y\frac{dy}{dx}+x\frac{dy}{dx}=-y

Factor out \frac{dy}{dx}

=\frac{dy}{dx}(2y+x)=-y

∴\frac{dy}{dx}=\frac{-y}{2y + x}

10.

A linear transformation on the oxy plane is defined by P : (x, y) → (2x + y, -2y). Find P^2

A.

\begin{bmatrix} 4&0\\1&4\end{bmatrix}

B.

\begin{bmatrix} 4&4\\0&0\end{bmatrix}

C.

\begin{bmatrix} 4&0\\0&4\end{bmatrix}

D.

\begin{bmatrix} 4&1\\0&4\end{bmatrix}

Correct answer is C

P : (x, y) → (2x + y, -2y)

p\begin{bmatrix} x\\y\end{bmatrix}=\begin{bmatrix} 2x & y\\0 &-2y\end{bmatrix}

\therefore p = \begin{bmatrix} 2 & 1\\0 &-2\end{bmatrix}

\therefore p^2 = \begin{bmatrix} 2&1\\0&-2\end{bmatrix} \begin{bmatrix} 2&1\\0&-2\end{bmatrix} = \begin{bmatrix} 4&0\\0&4\end{bmatrix}