Let’s assume the length of each train is ‘L’ and the speeds of the two trains are ‘V₁’ and ‘V₂’ respectively.
When the trains are moving in the opposite direction, their relative speed is the sum of their individual speeds. The total distance they need to cover is the sum of their lengths. Since they cross each other completely in 5 seconds, we can set up the following equation:
(V₁ + V₂) × 5 = 2L
When the trains are moving in the same direction, their relative speed is the difference between their individual speeds. The total distance they need to cover is the difference between their lengths. Since they cross each other completely in 15 seconds, we can set up the following equation:
(V₁ – V₂) × 15 = 2L
Now, let’s solve these equations to find the ratio of their speeds.
From the first equation, we have:
(V₁ + V₂) × 5 = 2L
V₁ + V₂ = (2L) / 5
From the second equation, we have:
(V₁ – V₂) × 15 = 2L
V₁ – V₂ = (2L) / 15
Let’s add these two equations together:
V₁ + V₂ + V₁ – V₂ = (2L) / 5 + (2L) / 15
2V₁ = (6L + 2L) / 15
2V₁ = (8L) / 15
V₁ = (4L) / 15
So, the speed of the first train is (4L) / 15.
Now, let’s substitute this value back into the first equation to find V₂:
(4L) / 15 + V₂ = (2L) / 5
V₂ = (2L) / 5 – (4L) / 15
V₂ = (6L – 4L) / 15
V₂ = (2L) / 15
Therefore, the speed of the second train is (2L) / 15.
The ratio of their speeds is given by:
(V₁ / V₂) = ((4L) / 15) / ((2L) / 15)
(V₁ / V₂) = 4L / 2L
(V₁ / V₂) = 2
So, the ratio of their speeds is 2:1.
12
((15 X m) + 23)/(m+1)= 16
solving , we get number of matches (m) as 7 (excluding last
match)
so he shud hit 39 runs in last innings to ake average to 18
10%
Ravi do a work in 30 days
Prakash do a work in 40days
then both work together 1/30+1/40=70/1200
then solve values 120/7 is 17(1/7) days
LCM=48
Then add remainder 3
ans =51
Train speed 90 km /h
1st we have to change in m/s. then 90*5/18=25m/s
Then d=speed*time
=25*10=250m train length
sister
66 seconds
The first 10 odd prime numbers are 3, 5, 7, 11, 13, 17, 19, 23, 29 and 31.
Sum of the odd prime numbers = (3+5+7+11+13+17+19+23+29+31)
= 158
Number of odd prime numbers = 10
We know, Average = (sum of the 10 odd prime numbers ÷ Number of odd
prime numbers)
Average =
= 15.8
∴ The Average of first 10 prime numbers which are odd is 15.8
Joe is fencing in a square area of 576 square feet.
Fence posts, which are needed every three feet, cost 32.00 each.
The fencing cost 4.50 per foot. What is the total cost of the fencing materials?
Solution:-
Area of Square is 576 sq ft.
so, the length of side = root(576) = 24 ft
Since the fencing would be done on the perimeter, we would need that
formula is 4*side = 96 ft.
Number of Fence post needed = 96/3 = 32
1 Fence post cost = 32
32 Fence Post cost = 32 * 32 = 1024
Fencing cost = Perimeter * fencing cost = 96 * 4.5 = 432
Total Cost = 432 + 1024 = 1456
democrate=1008