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Q:

In a group of 6 boys and 4 girls, four children are to be selected. In how many different ways can they be selected such that at least one boy should be there ?

A) 205	B) 194
C) 209	D) 159

Answer & Explanation Answer: C) 209

Explanation:

We may have (1 boy and 3 girls)or(2boys and 2 girls)or(3 boys and 1 girl)or(4 boys).

Required number of ways = ( ${}^{6}C_{1} \times {}^{4}C_{3}$ ) + $({}^{6}C_{2} \times {}^{4}C_{2})$ + ( ${}^{6}C_{3} \times {}^{4}C_{1}$ ) + ( ${}^{6}C_{4}$ )

= (24+90+80+15)

= 209.

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Filed Under: Permutations and Combinations
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Q:

In a bag, there are 8 red, 7 blue and 6 green flowers. One of the flower is picked up randomly. What is the probability that it is neither red nor green ?

$A) \frac{1}{3}$

$B) \frac{8}{21}$

$C) \frac{6}{21}$

$D) \frac{20}{21}$

A) Option A	B) Option B
C) Option C	D) Option D

Answer & Explanation Answer: A) Option A

Explanation:

Total number of flowers = (8+7+6) = 21.

Let E = event that the flower drawn is neither red nor green.

= event taht the flower drawn is blue.

--> n(E)= 7

--> P(E)= $\frac{7}{21}$ = $\frac{1}{3}$

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Filed Under: Permutations and Combinations
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Q:

A box contains 5 green, 4 yellow and 5 white pearls. Four pearls are drawn at random. What is the probability that they are not of the same colour ?

A) 11/91

B) 4/11

C) 1/11

D) 90/91

A) Option A	B) Option B
C) Option C	D) Option D

Answer & Explanation Answer: D) Option D

Explanation:

Let S be the sample space. Then,
n(s) = number of ways of drawing 4 pearls out of 14

= $C_{4}^{14}$ ways = $\frac{14 \times 13 \times 12 \times 11}{4 \times 3 \times 2 \times 1}$ = 1001

Let E be the event of drawing 4 pearls of the same colour.
Then, E = event of drawing (4 pearls out of 5) or (4 pearls out of 4) or (4 pearls out of 5)

$\Rightarrow C_{1}^{5} + C_{4}^{4} + C_{1}^{5}$ = 5+1+5 =11

P(E) = $\frac{n (E)}{n (S)} = \frac{11}{1001} = \frac{1}{91}$

Required probability = $1 - \frac{1}{91} = \frac{90}{91}$

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Filed Under: Permutations and Combinations
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Q:

Twenty men can do a work in eighteen days. Eighteen women can complete the same work in fifteen days. What is the ratio between the capacity of a woman and a man ?

A) 4:5	B) 3:4
C) 4:3	D) 2:3

Answer & Explanation Answer: C) 4:3

Explanation:

(20 x 18) men can complete the work in in one day.

one man's one day work = 1/360

(18 x 15) women can complete the work in 1 day

1 woman's one day work = 1/270

So, required ratio = $\frac{1}{270} : \frac{1}{360}$ = 4:3

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Filed Under: Time and Work
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Q:

Raghu can complete a work in 12days working 9 hours a day. Arun can complete the same work in 8 days working 11 hours a day. If both Raghu and Arun work together, working 12 hours a day, in how many days can they complete the work ?

A) $3 \frac{4}{49} d a y s$

B) $12 \frac{4}{49} d a y s$

C) $4 \frac{3}{49} d a y s$

D) $4 \frac{12}{49} d a y s$

A) Option A	B) Option B
C) Option C	D) Option D

Answer & Explanation Answer: C) Option C

Explanation:

Raghu can complete the work in (12 x 9)hrs = 108 hrs.

Arun can complete the work in (8 x 11)hrs = 88 hrs.

Raghu's 1 hrs work = 1/108 and Arun's 1 hrs work = 1/88

(Raghu + Arun)'s 1 hrs work = $(\frac{1}{108} + \frac{1}{88}) = \frac{49}{2376}$

So, both Raghu and Arun will finish the work in $\frac{2376}{49} h r s$

Number of days of 12 hours each= $(\frac{2376}{49} \times \frac{1}{12})$ = $\frac{198}{49} = 4 \frac{3}{49} d a y s$

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Q:

P and Q can do a work in 4 hours and 12 hours respectively. P starts the work at 9am and they work alternately for one hour each. When will the work be completed ?

A) 3 am	B) 12 pm
C) 1 pm	D) 3 pm

Answer & Explanation Answer: D) 3 pm

Explanation:

Work done by P and Q in the first two hours, working alternately

= First hour P + Second hour Q

$\Rightarrow \frac{1}{4} + \frac{1}{12} = \frac{1}{3}$

work is completed in 2 hours

Then, the total time required to complete the work by P and Q working alternately=2 x 3= 6hours

Thus, work will be completed at 3pm.

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Filed Under: Time and Work
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Q:

I travel 20 miles towards north and then travel 25 miles eastward. I then travel 40 miles rightwards, then travel 30 miles towards left and then travels 12 miles to the left and finally 20 miles northwards. How far am i pproximately from my original destination and in what direction ?

A) 20 miles towards south	B) 13 miles towards south-west
C) 12 miles towards east	D) 13 miles towards north-east

Answer & Explanation Answer: B) 13 miles towards south-west

Explanation:

k41483341709.jpg image

Using pythagorus rule,

$x^{2} = 12^{2} + 5^{2}$

--> x = 13

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Filed Under: Direction Sense Test
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Q:

Which Wins Patent for Flying Warehouse to Deliver Parcels via Drones ?

A) Flipkart	B) Snapdeal
C) Amazon	D) Paytm

Answer & Explanation Answer: C) Amazon

Explanation:

The U.S. e-commerce giant, Amazon has been awarded a patent for launching a giant flying warehouse that would acts as a launch pad for drones to deliver items within minutes.The patent reveals plans for setting up an “Airborne Fulfillment Center” (AFC) such as an Airship or Blimp, floating at an altitude of around 45,000 and stocked with lots of products especially in area where the demand for certain items is expected to be high. When a customer places an order, a drone or unmanned aerial vehicles (UAV) will fly down and deliver the package. The patent claims that this would require little or no power because the drone would be gliding down rather than having to take off and land.

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Filed Under: General Awareness
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