1. Ratan takes turns to cycle around the circular garden and through the diameter of the garden on alternate days. His speed each day is 6m/min but when he cycles through the diameter, he takes 1 hr less to cross the park. Find the diameter of the park.
A. 1530 m
B. 1680 m
C. 1750 m
D. 3600 m
Answer: Option B
Explanation:
We know that, Time =[latex]\frac {Distance}{Speed}[/latex]
Speed = 60m/min = [latex]\frac {60}{60}[/latex] m/sec = 1 m/sec
We know that,
Time along the park (circumference) - Time along the diameter = 60 minutes
∴[latex]\frac {2πr}{1}[/latex] - [latex]\frac {2r}{1}[/latex] = 60 minutes
∴ 2r ([latex]\frac {22}{7}[/latex]- 1) = 3600 seconds
∴ r = 840m
∴ Diameter = 2 x radius = 1680m.
2. Working alone Pramod takes complete April to build pavement. His friend Kishan is 25% faster than him at the same work. Working alone, how many days will Kishan take to build the same pavement?
A. 20 days
B. 24 days
C. 22.5 days
D. 37.5 days
Answer: Option B
Explanation:
April has 30 days. So Pramod takes 30 days to build the pavement.
Kishan is 25% faster than Pramod
25% =[latex]\frac {25}{100}[/latex] = 0.25
This means, if Pramod is 1, then Kishan is (1+0.25) = 1.25
Pramod takes 30 days to do the work.
Kishan will take = [latex]\frac {30}{1.25}[/latex]= 24 days to get the work done.
3. An 80L solution of alcohol and water has 45% alcohol in it. If you want the mixture to be 75% alcohol, how much alcohol would you add to it?
A. 30 litres
B. 75 litres
C. 96 litres
D. 110 litres
Answer: Option C
Explanation:
Current alcohol quantity =[latex]\frac {45}{100}[/latex]x 80 = 36 Litres
Let A be alcohol added.
So, 36 + A =[latex]\frac {75}{100}[/latex] x (80+A)
∴ A = 96 Litres = This is the additional quantity of alcohol to be added.
4. The price of commodity P increases by 40 paise every year, while the price of commodity Q increases by 15 paise every year. If in 2001, the price of commodity P was Rs. 4.20 and that of Q was Rs. 6.30, in which year commodity P will cost 40 paise more than the commodity Q?
A. 2008
B. 2009
C. 2010
D. 2011
Answer: Option D
Explanation:
Let the commodity P costs 40 paise more than the commodity Q after n years.
Price of the commodity P in 2001 = Rs.4.20
Since the price of the commodity P increases by Rs 0.40 every year,
Price of the commodity P after n years from 2001 = Rs.4.20 + (n × .40)
Price of the commodity Q in 2001 = Rs.6.30
Since the price of the commodity Q increases by Rs 0.15 every year,
price of the commodity Q after n years from 2001 = Rs.6.30 + (n × .15)
Since the commodity P costs Rs. 0.40 more that the commodity Q after n years from 2001,
4.20 + (n × .40) = 6.30 + (n × .15) + 0.40
=> (40n - .15n) = 6.30 - 4.20 + 0.40 = 2.5
=> .25n = 2.5
=> n = [latex]\frac {2.5}{.25}[/latex] = [latex]\frac {250}{25}[/latex] = 10
=> Commodity P costs Rs.0.40 more that the commodity Q after 10 years from 2001.
i.e., in 2011.
5. Prithvi rolled a dice twice and he saw that the addition of two numbers that appeared on the top face was 8. Find the probability of getting a 4 on the top face of the dice in the first throw.
A. [latex]\frac {1}{36}[/latex]
B. [latex]\frac {2}{36}[/latex]
C. [latex]\frac {1}{6}[/latex]
D. [latex]\frac {1}{5}[/latex]
Answer: Option A
Explanation:
A dice has 6 faces.
So there are 6 possible outcomes
Dice is rolled once AND then again.
So total possibilities = 6 x 6 = 36
The sum should be 8 of the 2 throws.
So which combination of numbers from 1 to 6 will yield us a sum of 8?
They are - (2,6); (6,2); (3,5); (5,3); (4,4)
So there are total 5 possibilities where addition is 8.
But only 1 possibility where first throw of dice is 4.
So, Probability for the first throw to be 4 and sum to be 8 = [latex]\frac {1}{36}[/latex]