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BBB 2022 - Senior Secondary - Preliminary Round

Question 1

It is known that $x$ is rational, $x>0$ and $x=5+\frac{14}{5+\frac{14}{5+\cdots}}$. Find the value of $x$.
  1. 5
  2. 8
  3. 7
  4. 6

Question 2

An interior angle of a regular $n$-sided polygon is $(12n-24)^\circ$. Find the value of $n$.
  1. 13
  2. 15
  3. 14
  4. 12

Question 3

$x$ is an acute angle and satisfies $\cot x=\frac34$. Find the value of $\frac{\sin^2x+\cos^2x}{\cos^2x-\sin^2x}$.
  1. $-\frac{25}7$
  2. $-\frac{12}7$
  3. $-\frac{16}7$
  4. $\frac97$

Question 4

In a rectangular coordinate system, a triangle is formed by vertices $A(5,3)$, $B(-1,4)$, $C(x,y)$. If the centroid of this triangle is $(4,2)$, find the value of $x-y$.
  1. 10
  2. 9
  3. 8
  4. 7

Question 5

How many integral solution(s) is / are there for $x$ if $2\le\frac{(x-3)^2}{2}-5\le12$?
  1. 2
  2. 4
  3. 6
  4. 21

Question 6

There are 20 students in a class. In how many different ways can the teacher choose 1 monitor and 2 vice-monitors?
  1. 2280
  2. 1140
  3. 6840
  4. 3420

Question 7

A straight line L passes through points $A(x,7)$ and $B(2,1)$ with the slope 3. Find $x$.
  1. 4
  2. 3
  3. 5
  4. 6

Question 8

Three identical cubes are combined to form one large cuboid with surface area of 224cm². Find the volume of that cuboid.
  1. 1029 cm³
  2. 648 cm³
  3. 192 cm³
  4. 1536 cm³

Question 9

If $y=\frac{-12}{x^2+6x+6}$ and $x,y$ are integers, find the maximum value of $y$.
  1. 3
  2. 4
  3. 6
  4. 12

Question 10

The radius of a sector is 8 and its perimeter is 50. Find the area of this sector.
  1. 136
  2. 272
  3. 68
  4. 34

Question 11

Find the area of the region bounded by the $y$-axis and two lines with the equation $x+2y-1=0$ and $2x-y-7=0$.
  1. 5.25
  2. 9.75
  3. 11.25
  4. 3.75

Question 12

How many factors of 12000 are square numbers?
  1. 4
  2. 6
  3. 8
  4. 10

Question 13

Given that $f(x)=\sum_{n=1}^{x}(-1)^{n-1}\frac n3$ for every positive integer $x$. Find the value of $f(2022)$.
  1. −337
  2. 337
  3. 674
  4. −674

Question 14

Find the value of $x$ in the system of equations.

$\begin{cases}2x+y+z=-6\\x-y+2z=-6\\x+3y+z=5\end{cases}$
  1. 6
  2. 5
  3. −5
  4. −6

Question 15

Given that $a>b>c$ and $\overline{12a3b456c}$ is divisible by 44. Find the greatest value of $\overline{abc}$.
  1. 980
  2. 974
  3. 984
  4. 970

Question 16

Given $x$ and $y$ are positive integers and $2022^x+2023^y$ can be divisible by 11, find the minimum value of $x+y$.
  1. 7
  2. 4
  3. 5
  4. 6

Question 17

Given a square. Wendy draws 4 semi-circles quarters whose diameters are the sides of the square as follows. If the area of the shaded region is $8\pi-16$, find the area of the white region.

Question illustration
  1. $32-8\pi$
  2. $8\pi$
  3. $8\pi-16$
  4. $32-16\pi$

Question 18

In $\triangle ABC$, $AB=12$, $BC=6$ and $B=60^\circ$, find the value of $\frac{\sin B}{\sin A}$.
  1. $\sqrt3$
  2. $6\sqrt3$
  3. $\frac{\sqrt3}2$
  4. $\frac{\sqrt3}6$

Question 19

Numbers are drawn from 2000 integers 1 to 2000. At least how many numbers are drawn at random to ensure that there are two numbers whose product is 3600?
  1. 1979
  2. 1956
  3. 1958
  4. 1980

Question 20

There are 3 black balls and 2 white balls. If 5 balls are drawn randomly one by one without replacement, find the probability that the 2nd one is a white ball.
  1. $\frac25$
  2. $\frac45$
  3. $\frac35$
  4. $\frac15$