A die is tossed once, the probability of getting a number smaller than 8 is :

1. 0

2. 1

3. $\dfrac{1}{2}$

4. $\dfrac{3}{4}$

If matrix P = $\begin{bmatrix$}[r] -2 & 0 \ 4 & -3 \end{bmatrix}, then P² is :

1. $\begin{bmatrix$}[r] 4 & 0 \ -20 & 9 \end{bmatrix}

2. $\begin{bmatrix$}[r] 4 & 0 \ -20 & -9 \end{bmatrix}

3. $\begin{bmatrix$}[r] -4 & 0 \ -20 & 9 \end{bmatrix}

4. $\begin{bmatrix$}[r] 4 & 0 \ 20 & -9 \end{bmatrix}

A solid sphere and a solid hemisphere have the same total surface area. The ratio of their diameters is :

1. $\sqrt{2} : 3$

2. 3 : 2

3. $\sqrt{3} : 2$

4. 3 : $\sqrt{2}$

△ABC and △PQR are similar to each other. If ∠A = 45° and ∠R = 55°; then angle B is equal to :

1. 55°

2. 80°

3. 100°

4. 90°