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Q:

Two boys starting from the same place walk at a rate of 5kmph and 5.5kmph respectively. What time will they take to be 8.5km apart, if they walk in the same direction?

A) 15 hours	B) 16 hours
C) 17 hours	D) 18 hours

Answer & Explanation Answer: C) 17 hours

Explanation:

In this type of questions we need to get the relative speed between them,
The relative speed of the boys = 5.5kmph – 5kmph
= 0.5 kmph

Distance between them is 8.5 km
Time = Distance/Speed
Time= 8.5km / 0.5 kmph = 17 hrs

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Filed Under: Time and Distance
Exam Prep: GRE

Q:

A man in a train notices that he can count 41 telephone posts in one minute. If they are known to be 50 metres apart, then at what speed is the train travelling?

A) 60 km/hr	B) 100 km/hr
C) 110 km/hr	D) 120 km/hr

Answer & Explanation Answer: D) 120 km/hr

Explanation:

Number of gaps between 41 poles = 40
So total distance between 41 poles = 40*50
= 2000 meter = 2 km
In 1 minute train is moving 2 km/minute.
Speed in hour = 2*60 = 120 km/hour

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Filed Under: Time and Distance
Exam Prep: GRE

Q:

The atoms of the elements having same mass number but different atomic number are called

A) Isotopes	B) Isobars
C) Isotones	D) Isomers

Answer & Explanation Answer: B) Isobars

Explanation:

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Filed Under: Chemistry

Q:

Cobalt - 60 is commonly used in radiation therapy because it emits

A) alpha - rays	B) beta rays
C) gamma rays	D) X - rays

Answer & Explanation Answer: C) gamma rays

Explanation:

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Filed Under: Chemistry

Q:

Which one of the following can be used to confirm wether drinking water contains a gamma emitting isotope or not

A) Microscope	B) Scintillation counter
C) Lead plate	D) pectrophotometer

Answer & Explanation Answer: B) Scintillation counter

Explanation:

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Filed Under: Chemistry

Q:

In atomic reactors,graphite is used as

A) lubricant	B) fuel
C) linear of the ractor	D) moderator

Answer & Explanation Answer: D) moderator

Explanation:

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Filed Under: Chemistry

Q:

At what time between 2 and 3 o'clock will the hands of a clock be together?

A) (9 + 10/11) min past 2	B) (10 + 10/11) min past 2
C) (11 + 10/11) min past 2	D) (12 + 10/11) min past 2

Answer & Explanation Answer: B) (10 + 10/11) min past 2

Explanation:

At 2 o'clock, the hour hand is at 2 and the minute hand is at 12, i.e. they are 10 min spaces apart.

To be together, the minute hand must gain 10 minutes over the hour hand.

Now, 55 minutes are gained by it in 60 min.

$\therefore$ 10 minutes will be gained in $\frac{60}{55} \times 10$ min. = $10 \frac{10}{11}$ min.

The hands will coincide at $10 \frac{10}{11}$ min. past 2.

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

Q:

At what time between 9 and 10 o'clock will the hands of a watch be together?

A) (49 + 3/11) min past 11	B) (49 +1/11) min past 9
C) (45 +1/11) min past 9	D) (45 +7/11) min past 11

Answer & Explanation Answer: B) (49 +1/11) min past 9

Explanation:

To be together between 9 and 10 o'clock, the minute hand has to gain 45 min. spaces.
55 min. spaces gained in 60 min.

45 min. spaces are gained in $\frac{60}{55} \times 45$ min or $49 \frac{1}{11}$ min

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

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