The probability that a child will be born male on any given day is always 1/2.
Suppose:
In any time period, the family making out babies and half boys and another half girls then, In the next time period: half the families turn themselves off and again the half remaining families making out the babies which repeat the first period.
Previous their age was 21 and 18 respectively
Presently, after 6 years the age is 27 and 24.
Let the journey distance be : x miles
Now x/40+x/30=8 (time=distance/speed)
Solving this for x we get. x=960/7
therefore, x=137(approx)
(137.14 exact)
1200 meter
7 : 3
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.
10.66 kmph
23
under pressure a person more effort to his work
Books=65+50=>115
Prices=1150+920=>2070
2070/115
18
In a cube all the diagonal and sides are equal, we can go diagonally.
Let three consecutive even numbers be 2n,2n+2,2n+4
product=2n(2n+2)(2n+4)
If n=1,
product =2(4)(6)=48.
So, all the numbers will be divisible by 48 if change n.
297
A
At 680Km