A polygon has 44 diagonals, the number of its sides are?
A)
9
B)
10
C)
11
D)
12
Your Answer : (Not Answered) Correct Answer :
11
Explanation :
Polygon: A polygon is a 2-dimensional shape that is formed with straight lines. Triangles, quadrilaterals, pentagons, and hexagons are all examples of polygons.
Let the side is n. because there are n sides, we have to subtract n from total number of line formed by joining two adjacent vertices of polygon.
number of diagonals = nC2 -n = n(n-1)/2 - n
number of diagonals = n(n-3) / 2 = 44
n2 - 3n - 88 = 0
(n+3) (n-11) = 0
n=11 (n can not be negative)
So the number of sides in a shape with 44 diagonals is 11.
If the perimeter of a rectangle is 10 cm and the area is 4 cm2, then its length is?
A)
6 cm
B)
5 cmm
C)
4.5 cm
D)
4 cm
Your Answer : (Not Answered) Correct Answer :
4 cm
Explanation :
Let l and b the length and breadth of the rectangle respectively.
Now, according to the question 2(l + b) = 10
l + b = 5 …eq(i)
and lb = 4 …eq(ii)
From Eqs. (i) and (ii), we have
l(5 - l) = 4
5l - l2 = 4
l2 - 5l + 4 = 0
(l - 4)(l - 1) = 0
If the length of a certain rectangle is decreased by 4 cm and the width is increased by 3 cm, a square with the same area as the original rectangle would result. Find the perimeter of the original rectangle?
A)
40 cm
B)
50 cm
C)
60 cm
D)
30 cm
Your Answer : (Not Answered) Correct Answer :
50 cm
Explanation :
Let x and y be the length and breadth respectively.
Area of rectangle = x*y
Area of square = (x-4) * (y+3)
As is given , (x-4) * (y+3)= x*y
3x – 4y = 12 ……………………………….(i)
for a square, length = width
(x-4) = (y+3)
x - y = 7 ……………………………….(ii)
Solving eq (i) & (ii) x= 16 and y = 9
Therefore perimeter of rectangle = 2(x+y)= 2(16+9)= 50 cm
The average of first three numbers out of four numbers are 18 and the average of the last three numbers is 16. If the last number is 19, then the first number is?
A)
19
B)
18
C)
20
D)
25
Your Answer : (Not Answered) Correct Answer :
25
Explanation :
Let the numbers are A, B ,C and D, then as given
A+B+C=18*3=54
B+C+D=16*3=48
After resolving the above equations -
A-D=6
the last number is 19 ie D=19
So, A=6+19 =25
Let 5x = y , then
5y2 - 26y +5 = 0
5y2 - 25y - y + 5 = 0
5y( y - 5) - 1( y - 5) = 0
( y - 5)(5y - 1) = 0
y = 5 , 1/5
that is , 5x = 5 or 5-1
therefore x = 1 , -1
A, B and C can complete one task alone in 10 days, 12 days and 15 days respectively. If they start working together, then the number of days required to complete the work?
A)
12 days
B)
10 days
C)
8 days
D)
4 days
Your Answer : (Not Answered) Correct Answer :
4 days
Explanation :
(A+B+C)'s one days work= 1/10 + 1/12 + 1/15 = 6+5+4/60 = 15/60 = 1/4
Hence, (A+B+C) can work together in 4 days
6 children and 2 men complete a certain piece of work in six days. Each child takes twice the time taken by a man to finish the work. In how many days will 5 men finish the same work?
A)
6
B)
8
C)
9
D)
15
Your Answer : (Not Answered) Correct Answer :
6
Explanation :
6C + 2M = 6 days
36C + 12M = 1 day
As is given 1M = 2C
Then, 36C +12*2C = 1 day
60 children can work in 1 day
Now, 5 men = 10 children
Then, 10 children can work in 6 days.So 5 men also can complete the work in 6 days.
The speed of a boat downstream is 15 km/hr and the speed of the stream is 1.5 km/hr. The speed of the boat upstream is ?
A)
13.5 km/hr
B)
16.5 km/hr
C)
12 km/hr
D)
8.25 km/hr
Your Answer : (Not Answered) Correct Answer :
12 km/hr
Explanation :
If The speed of boat or boatman in calm water is u kmph and The speed of water or stream is v kmph, then:
Speed downstream= (u + v) kmph , In water, the speed along with stream
Speed upstream = (u - v) kmph ,In water, the speed against the stream
15= u + 1.5
⇒ u = 13.5
Speed upstream, u - v = (13.5 - 1.5) km/hr = 12 km/hr