1988 年

The line $y=mx+c$ is perpendicular to the line $y=3-2x$. Find $m$.

In the figure, $A(5,3)$, $B(b,1)$ and $C(c,1)$ are the vertices of a triangle. If $AB=AC$, then $b+c=$

The maximum load a lift can carry is $600\text{ kg}$. $11$ men with a mean weight of $49\text{ kg}$ are already in the lift. If one more man is to enter the lift, his weight must not exceed

The mean length of $30$ rods is $80\text{ cm}$. If one of these rods of length $68\text{ cm}$ is taken out and replaced by another rod of length $89\text{ cm}$, then the new mean length is

The figure shows 3 paths joining $A$ and $B$. A man walks from $A$ to $B$ and another man walks from $B$ to $A$ at the same time. If they choose their paths at random, what is the probability that they will meet?

The figure shows the cumulative frequency polygon of the heights of 100 persons. If one person is selected at random from the group, find the probability that his height is less than $170\text{ cm}$ but not less than $150\text{ cm}$.

Which of the following expressions CANNOT be factorized?

If $\log a>0$ and $\log b<0$, which of the following is/are true?

I. $\log\dfrac{a}{b}>0$ II. $\log b^2>0$ III. $\log\dfrac{1}{a}>0$

In the figure, which region represents the solution to the following inequalities? $\begin{cases}x-3y\le 0\\x-y+2\ge 0\\x+y-4\ge 0\end{cases}$

$p, q, r, s$ are in A.P. If $p+q=8$ and $r+s=20$, then the common difference is