A man goes uphill with an average speed of 35 km/hr, and covers down with an average speed of 45 km/hr. The distance travelled in both the cases being the same , the average speed for the entire journey is ?
A)
315/8 km/hr
B)
325/8 km/hr
C)
40 km/hr
D)
315 km/hr
Your Answer : (Not Answered) Correct Answer :
315/8 km/hr
Explanation :
When d1 = d2 , Average speed = 2*S1*S2/(S1+S2), where S1 and S2 are the speeds for covering d1 and d2 respectively
In a box there are 4 black, 4 orange and 2 blue marbles. Two marbles are drawn at random. What is the probability that at least one marble is of blue colour?
A)
4/5
B)
3/5
C)
1/5
D)
None of these
Your Answer : (Not Answered) Correct Answer :
None of these
Explanation :
total numbers of marbles in box= 4 black+4 orange+2 blue=10 marbles
sample space n(S)=number of ways of drawing two marbles out of 10 marbles from box= 10C2 =10!/2!*8! =10*9/2*1 =45
event of picking two marble those are not blue from out of (4 black+4 orange) 8 marbles, n(E)=8C2=8!/2!*6! =8*7/2*1=28
hence probability of drawn two marble from box which not blue p(E)=n(E)/n(S)=28/45
So probability to drown atleast one marble is blue=1-28/45=(45-28)/45=37/45
PQRS is the greatest number of 4 digits which when divided by any of the numbers 6, 9, 12 or 17 leaves a remainder of 2 in each case. What is the value of (P + R)/(Q + S)?
A)
18
B)
18/11
C)
11/18
D)
9/11
Your Answer : (Not Answered) Correct Answer :
18/11
Explanation :
The required number, which is exactly divisible by each one of the given numbers, should be divisible by LCM of (6, 9, 12, 17) i.e. 612
The Largest number of four digits is 9999.by dividing 9999 to 612 get 207 as remainder.
So, the greatest number of 4 digits divisible by any numbers from 6, 9, 12 or 17 = (9999-207) = 9792.
But we should get the remainder as 2,so we need to add 2 to 9792.So the number PQRS is 9794.
Find the sum of the first 20 terms of the series : 8, -3, 11, -6, 14, -12, 17, -24,....... ?
A)
-2854
B)
2854
C)
-3069
D)
3069
Your Answer : (Not Answered) Correct Answer :
-2854
Explanation :
8, -3, 11, -6, 14, -12, 17, -24,.......
odd term: next value is +3 of previous one
8, (+3) 11,(+3)14,(+3) 17...-3, -6, -12, -24, -48, -96, -192, -384, -768, -1536
8, 11, 14, 17, 20, 23, 26, 29, 32, 35
total => 215
even term: next value is double of previous one
-3, (-3*2) -6, (-6*2) -12, (-12*2) -24....
-3, -6, -12, -24, -48, -96, -192, -384, -768, -1536
total => -3069
The average mark of 50 students is 75. If the marks obtained by one of the student had been written as 36 instead of 86, then the corrected average of marks is:
A)
51
B)
76
C)
36
D)
61
Your Answer : (Not Answered) Correct Answer :
76
Explanation :
Sum of values = Average of values × Number of values
The total marks obtained by 50 students = 75 * 50 = 3750
Marks of one student is written as 36 instead of 86.
Actual marks = 3750 + (86 – 36)
=3750 + 50
=3800
Hence correct average = Actual marks/total number of students
=3800/50
=76
Shantanu was given a task of adding a certain number of consecutive natural numbers starting from 1. By mistake, he missed a number during addition. He obtained the sum as 800. Find the number that he missed?
A)
15
B)
20
C)
25
D)
10
Your Answer : (Not Answered) Correct Answer :
20
Explanation :
Sum of n natural numbers is n(n+1)/2 ,and let missing number is x (x<=n) ,then
=> n(n+1)/2 = 800+x
n(n+1) = 1600+2x
It seems that n2 is approximate to 1600, then
n2=402
n=40 and , n+1=41
Therefore n(n+1) = 1600+2x
=> 40*41 =1600+2x
1640 =1600+2x
x = 20
Thus, 20 is the number that he missed.
How many groups of 6 persons can be formed from 8 men and 7 women ?
A)
5000
B)
5005
C)
5050
D)
5650
Your Answer : (Not Answered) Correct Answer :
5005
Explanation :
Total number of person = 8 men + 7 women = 15
No. of groups can be formed of 6 persons= 15C6 = 15! / {6! *(15 - 6)!} = 15! / (6! * 9!)
= (15 x 14 x 13 x 12 x 11 x 10) / (6 x 5 x 4 x 3 x 2 x 1)
= 5005
A copper wire when bent in the form of a square encloses an area of 121 cm2. If the same wire is bent in the form of a circle, it encloses an area equal to?
A)
121 cm2
B)
144 cm2
C)
154 cm2
D)
168 cm2
Your Answer : (Not Answered) Correct Answer :
154 cm2
Explanation :
As is given, area of square = a2 = 121 cm2
So, side of square, a = 11 cm
length of the wire = Perimeter of square of side a = 4a = 4*11 = 44cm
Let the radius of circle be r cm. Then,
Perimeter of circle = Length of wire
=> 2πr = 44 cm
=> r = 44/2π = 7 (π = 22/7)
A discount series of 10%, 20% and 40% is equal to single discount of ?
A)
50%
B)
56.80%
C)
70%
D)
70.28%
Your Answer : (Not Answered) Correct Answer :
56.80%
Explanation :
Let original price = Rs. 100
Price after 1 st discount = Rs. 90
Price after 2 nd discount = Rs. (80/100) x 90 = Rs. 72
Price after 3 rd discount = Rs. (60/100) x 72 = Rs. 43.20
A 5 cm cube is cut into as many 1 cm cubes as possible. What is the ratio of the surface area of the larger cube to the smaller cubes?
A)
1/6
B)
1/5
C)
1/25
D)
1/125
Your Answer : (Not Answered) Correct Answer :
1/5
Explanation :
The volume of the original cube = 53 = 125 cm3.
The volume of a smaller cubes = 13 = 1 cm3.
Therefore, we will be get total smaller cubes = 125/1 = 125
The surface area of the larger cube = 6*a2 = 6(52) = 6 * 25 = 150
The surface area of each of the smaller cubes = 6 (12) = 6.
Therefore, surface area of all of the 125, 1 cm3 cubes = 125 * 6 = 750.
The denominators of an irreducible fraction is greater than the numerator by 2.If we reduce the numerator of the reciprocal fraction by 3 and subtract the given fraction from the resulting one,we get 1/15.Find the given fraction?
A)
2/5
B)
2/3
C)
3/5
D)
5/3
Your Answer : (Not Answered) Correct Answer :
3/5
Explanation :
Let the numerator of the fraction be x.
It is given that the denominator of the fraction is greater than the numerator of the fraction by 2.
So the denominator becomes x+2.
Therefore, fraction be x/(x+2)
The product of two numbers is 192 and the difference is 4. These two numbers are?
A)
16, 12
B)
18, 14
C)
17, 13
D)
15, 11
Your Answer : (Not Answered) Correct Answer :
16, 12
Explanation :
let the numbers are x and x-4
product of number is x*(x-4) =192
x2-4x-192=0
x2-4x-192=0
x2-16x+12x-192=0
(x-16)(x+12)=0
So x either 16 or -12 and other number either 12 or -16
that both sets of answers will work. (12 * 16) = 192 , (-12 * -16) = 192
Ajay is 15 years elder than Rohan. If 5 years ago, Ajay was 3 times as old as Rohan, then find Ajay's present age.
A)
32.5 years
B)
27.5 years
C)
25 years
D)
24.9 years
Your Answer : (Not Answered) Correct Answer :
27.5 years
Explanation :
Let age of Rohan be y
Ajay is 15 years elder than Rohan,So Ajay’s age = (y + 15).
5 years ago, Ajay is 3 times as old as Rohan
(y + 15 – 5) = 3 (y – 5)
(y + 10) = (3y – 15)
2y = 25
y = 12.5
Rohan's age = 12.5 years
Ajay's age = (y + 15) = (12.5 + 15) = 27.5 years