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Q:

A number is selected at random from the numbers 1 to 30. What is the probability that it is divisible by either 3 or 7 ?

A) 1/30	B) 2/30
C) 1/25	D) 1/2

Answer & Explanation Answer: A) 1/30

Explanation:

Let A be event of selecting a number divisible by 3. B be the event of selecting a number divisible by 7.

A = { 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 }, so n(A)=10
B = { 7, 14, 21, 28 }, n(B)= 4

Since A and B are not mutually exclusive So :

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Filed Under: Probability

Q:

$i f \log \frac{a}{b} + \log \frac{b}{a} = \log (a + b), t h e n$

A) a + b = 1	B) a - b = 1
C) a = b	D) ab=1

Answer & Explanation Answer: A) a + b = 1

Explanation:

$i f \log \frac{a}{b} + \log \frac{b}{a} = \log (a + b), t h e n$

$\log (a + b) = \log (\frac{a}{b} \times \frac{b}{a}) = \log 1$

so, a+b=1

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Filed Under: Logarithms
Exam Prep: Bank Exams
Job Role: Bank PO

Q:

If each edge of a cube is increased by 50%, find the percentage increase in Its surface area

A) 125%	B) 150%
C) 175%	D) 110%

Answer & Explanation Answer: A) 125%

Explanation:

Let the edge = a cm

So increase by 50 % = a + a/2 = 3a/2

Total surface Area of original cube = $6 a^{2}$

TSA of new cube = $6 {(\frac{3 a}{2})}^{2}$ = $6 (\frac{9 a^{2}}{4})$ = $13.5 a^{2}$

Increase in area = $13.5 a^{2} - 6 a^{2}$ = $7.5 a^{2}$

$7.5 a^{2}$ Increase % = $\frac{7.5 a^{2}}{6 a^{2}} \times 100$ = 125%

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Filed Under: Volume and Surface Area

Q:

A cube of edge 15 cm is immersed completely in a rectangular vessel containing water . If the dimensions of the base of vessel are 20 cm x 15 cm, find the rise in water level

A) 11.25cm	B) 11.56cm
C) 11.66cm	D) 10.86cm

Answer & Explanation Answer: A) 11.25cm

Explanation:

Increase in volume = Volume of the cube = (15 x 15 x 15) cm3.

\Rise in water level = volume/area = (15 x 15 x 15)/(20 x 15) cm = 11.25 cm.

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Filed Under: Quantitative Aptitude - Arithmetic Ability

Q:

The dimensions of an open box are 50 cm, 40 cm and 23 cm. Its thickness is 2 cm. If 1 cubic cm of metal used in the box weighs 0.5 gms, find the weight of the box.

A) 8.04kg	B) 8.14kg
C) 8.24kg	D) 9.04kg

Answer & Explanation Answer: A) 8.04kg

Explanation:

Volume of the metal used in the box = External Volume - Internal Volume

= [(50 x 40 x 23) - (44 x 34 x 20)] cu.cm

= 16080 cu.cm

Weight of the metal =[(16080 x 0.5)/1000] kg = 8.04 kg.

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Filed Under: Volume and Surface Area

Q:

Water flows into a tank 200 m x 160 m through a rectangular pipe of 1.5m x 1.25 m @ 20 kmph . In what time (in minutes) will the water rise by 2 meters?

A) 92min	B) 93min
C) 95min	D) 96min

Answer & Explanation Answer: D) 96min

Explanation:

Volume required in the tank = (200 x 150 x 2) cu.m = 60000 cu.m

Length of water column flown in1 min =(20 x 1000)/60 m =1000/3 m

Volume flown per minute = 1.5 x 1.25 x (1000/3) cu.m= 625 cu.m.

Required time = (60000/625)min = 96min

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Filed Under: Volume and Surface Area

Q:

Find the number of bricks, each measuring 24 cm x 12 cm x 8 cm, required to construct a wall 24 m long, 8m high and 60 cm thick, if 10% of the wall is filled with mortar?

A) 35000	B) 45000
C) 55000	D) 65000

Answer & Explanation Answer: B) 45000

Explanation:

Volume of the wall = (2400 x 800 x 60) cu.cm

Volume of bricks = 90% of the volume of the wall

= [(90/100) x 2400 x 800 x 60] cu.cm

Volume of 1 brick = (24 x 12 x 8) cu.cm

Number of bricks = [(90/100) x (2400 x 800 x 60) ]/ (24 x 12 x 8) = 45000

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Filed Under: Volume and Surface Area

Q:

In a charity show tickets numbered consecutively from 101 through 350 are placed in a box. What is the probability that a ticket selected at random (blindly) will have a number with a hundredth digit of 2?

A) 0.25	B) 0.5
C) 0.75	D) 0.40

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