Polynomial Zeroes
1. **Problem:** Determine the number of zeroes of a polynomial graphically.
The zeroes of a polynomial are the values of $x$ for which the polynomial equals zero. Graphically, these correspond to the points where the graph intersects the $x$-axis.
**Answer:** (b) intersects x-axis
2. **Problem:** Find two successive integral multiples of 5 whose product is 300.
Let the two numbers be $5n$ and $5(n+1)$.
Their product is:
$$5n \times 5(n+1) = 25n(n+1) = 300$$
Simplify:
$$n(n+1) = \frac{300}{25} = 12$$
Solve the quadratic:
$$n^2 + n - 12 = 0$$
Factor:
$$(n+4)(n-3) = 0$$
So, $n = 3$ or $n = -4$.
Taking positive $n=3$, the numbers are:
$$5 \times 3 = 15, \quad 5 \times 4 = 20$$
**Answer:** (d) 15, 20
3. **Problem:** Find the ratio $a:b$ for the parallelogram with vertices $(-3,-1)$, $(a,b)$, $(3,3)$, and $(4,3)$.
In a parallelogram, the diagonals bisect each other.
Midpoint of diagonal 1:
$$M_1 = \left(\frac{-3 + 3}{2}, \frac{-1 + 3}{2}\right) = (0, 1)$$
Midpoint of diagonal 2:
$$M_2 = \left(\frac{a + 4}{2}, \frac{b + 3}{2}\right)$$
Since midpoints are equal:
$$\frac{a + 4}{2} = 0 \Rightarrow a + 4 = 0 \Rightarrow a = -4$$
$$\frac{b + 3}{2} = 1 \Rightarrow b + 3 = 2 \Rightarrow b = -1$$
Ratio:
$$a : b = -4 : -1 = 4 : 1$$
**Answer:** (a) 4 : 1
4. **Problem:** A man on a ship 10 m above water observes the angle of elevation of the hill top as $45^\circ$ and angle of depression of the hill base as $30^\circ$. Find the distance to the hill and its height.
Let the distance from the ship to the hill base be $d$.
From angle of depression $30^\circ$:
$$\tan 30^\circ = \frac{10}{d} \Rightarrow d = \frac{10}{\tan 30^\circ} = \frac{10}{\frac{1}{\sqrt{3}}} = 10\sqrt{3} \approx 17.32$$
From angle of elevation $45^\circ$:
Let height of hill be $h$.
$$\tan 45^\circ = \frac{h - 10}{d} = 1 \Rightarrow h - 10 = d \Rightarrow h = d + 10 = 17.32 + 10 = 27.32$$
**Answer:** (a) 17.32 m, 27.3 m
5. **Problem:** Find the area of the circle inscribed in a square of side 6 cm.
The inscribed circle touches all sides, so its diameter equals the side of the square.
Radius $r = \frac{6}{2} = 3$ cm.
Area:
$$\pi r^2 = \pi \times 3^2 = 9\pi$$
**Answer:** (c) 9\pi cm²
6. **Problem:** Mean of $x - 5y$, $x - 3y$, $x - y$, $x + y$, $x + 3y$, $x + 5y$ is 22. Find $x$.
Sum:
$$6x + (-5y - 3y - y + y + 3y + 5y) = 6x + 0 = 6x$$
Mean:
$$\frac{6x}{6} = x = 22$$
**Answer:** (b) 22
7. **Problem:** Probability that a leap year has 53 Fridays or 53 Saturdays.
A leap year has 366 days = 52 weeks + 2 days.
The 2 extra days can be:
- Sunday & Monday
- Monday & Tuesday
- Tuesday & Wednesday
- Wednesday & Thursday
- Thursday & Friday
- Friday & Saturday
- Saturday & Sunday
For 53 Fridays, the extra days must include Friday.
For 53 Saturdays, the extra days must include Saturday.
Possible pairs with Friday or Saturday:
- Thursday & Friday
- Friday & Saturday
- Saturday & Sunday
Number of favorable pairs = 3
Total possible pairs = 7
Probability:
$$\frac{3}{7}$$
**Answer:** (d) 3/7