Exams


Q:

The top and bottom of a tower were seen to be at angles of depression 30° and 60° from the top of a hill of height 100 m. Find the height of the tower ?

A) 42.2 mts B) 33.45 mts
C) 66.6 mts D) 58.78 mts
 
Answer & Explanation Answer: C) 66.6 mts

Explanation:

ht1488353450.jpg image

From above diagram
AC represents the hill and DE represents the tower

Given that AC = 100 m

angleXAD = angleADB = 30° (∵ AX || BD )
angleXAE = angleAEC = 60° (∵ AX || CE)

Let DE = h

Then, BC = DE = h, AB = (100-h) (∵ AC=100 and BC = h), BD = CE

tan 60°=AC/CE => √3 = 100/CE =>CE = 100/√3 ----- (1)

tan 30° = AB/BD => 1/√3 = 100−h/BD => BD = 100−h(√3)
∵ BD = CE and Substitute the value of CE from equation 1
100/√3 = 100−h(√3) => h = 66.66 mts

The height of the tower = 66.66 mts.

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Filed Under: Height and Distance
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Q:

Which physical connection is the fastest?

A) Coaxial cable B) Infrared
C) Microwave D) Fiber-optic
 
Answer & Explanation Answer: D) Fiber-optic

Explanation:

Fiber-optic physical or wired connection is the fastest communication connection.

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Q:

The compound interest on a certain sum for 2 years at 10% per annum is Rs. 1155. The simple interest on the same sum for double the time at half the rate percent per annum is ?

A) Rs. 1100 B) Rs. 5500
C) Rs. 1400 D) Rs. 4120
 
Answer & Explanation Answer: A) Rs. 1100

Explanation:

Let the sum be Rs.x. Then, 

 

 x1+101002-x=1155

 

x11102-1=1155

 

=> x =5500

 

sum = Rs. 5500.

 

So, S.I = Rs. 5500×5×4100 = 1100

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Filed Under: Compound Interest
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Q:

Website always has

A) Address B) Information
C) Attachments D) Images
 
Answer & Explanation Answer: A) Address

Explanation:

Website always has an address whether it has images, any information or any attchments in it or not but it must has an address. 

Website_always_has1551876614.jpg image

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Q:

Which of the following statements is not correct?

A) log10 = 1 B) log (2 + 3) = log (2 x 3)
C) log1 = 0 D) log (1 + 2 + 3) = log 1 + log 2 + log 3
 
Answer & Explanation Answer: B) log (2 + 3) = log (2 x 3)

Explanation:

log (2 + 3) = log 5

 

log (2 x 3) = log 2 + log 3

 


 log (2 + 3) log (2 x 3)

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Filed Under: Logarithms
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Q:

A shopkeeper sells two articles at Rs.1000 each, making a profit of 20% on the first article and a loss of 20% on the second article. Find the net profit or loss that he makes?

A) 2% B) 4%
C) 3% D) 2.5%
 
Answer & Explanation Answer: B) 4%

Explanation:

SP of first article = 1000

Profit = 20%

CP = 100100+P×SP= 5000/6 = 2500/3


SP of second article = 1000

Loss = 20%

CP = 100100-L×SP= 5000/4 = 1250


Total SP = 2000

Total CP = 25003+ 1250 = 6250/3

CP is more than SP, he makes a loss.

Loss = CP-SP = (6250/3)- 2000 = 250/3


Loss Percent =250362503×100= 4%

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Filed Under: Profit and Loss
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Q:

How long will it take for two pipes A and B to fill an empty cistern if they worked alternately for an hour each ?

A. Working alone, Pipe A can fill the cistern in 40 hours
B. Pipe B is one third as efficient as Pipe A

A) Only A is sufficient B) Only B is sufficient
C) Both (A) and (B) are sufficient D) None
 
Answer & Explanation Answer: C) Both (A) and (B) are sufficient

Explanation:

From statement A, we know that Pipe A can fill the tank in 40 hours. However, this information is not sufficient as we do not have the data for Pipe B. Hence, statement A alone cannot answer the given question.

From statement B, we know that Pipe B is one third as efficient as pipe A. However, we do not know the rate at which Pipe A fills the tank. Hence, we will not be able to find the rate at which Pipe B fills the cistern. Therefore, statement B alone is not sufficient to answer the question.

Now, if we combine the two statements, we know that Pipe A take 40 hours to fill the cistern.
Pipe B takes 120 hours to fill the cistern.

If they worked alternately, then either Pipe A could have started the cycle or Pipe B could have started the cycle.

If Pipe A started the sequence of filling alternately, then at the end of two hours, the two pipes together would have filled 1/40 + 1/120 = 1/30  th of the tank in an hour. Or the cistern will fill in 30 hours.

If Pipe B started the sequence, then at the end of 2 hours, the two pipes together would have filled 1/120 + 1/40 = 1/30 th of the tank in an hour. Or the cistern will fill in 30 hours.

As the answer obtained irrespective of which pipe started the sequence is the same, the correct answer is (3) - i.e., both the statement are sufficient to answer the question.

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Filed Under: Statement and Conclusions
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Q:

In the following question a number series is given which has only one wrong number. You have to find out the wrong number?

7.5  47.5  87.5  157.5  247.5  357.5  487.5 

A) 47.5 B) 87.5
C) 247.5 D) 357.5
 
Answer & Explanation Answer: A) 47.5

Explanation:
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Filed Under: Problems on Numbers
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