Two guns were fired from the same place at an interval of 20 minutes but a person in a train approaching the place hears the sound 16 minutes 30 seconds after the first. Find the speed of the train (in kmph) supposing that the sound travels 330 meters per second.
The distance travelled by the train in 16min 30 seconds will be equal to that travelled by sound (20 min – 16 min 30 sec) = 3 min 30 seconds The train travelled 330 × 210 meters in 16 1/2 minutes. ∴ Speed of the train per hour = (330 × 210 × 2 × 60)/(33 ×1000) = 252 km/hr ALTERNATE METHOD: Let speed of train = x m/s The distance covered by bullet with a speed of sound 330m/s in 20 minutes is equal to distance covered by train & bullet together in 16 min 30 sec So let speed of train = x m/s So 330 × 20 = (x+330) × 16 ×1/2 6600 × 2/33 = x + 330 So x + 330 = 400 Or x = 70 m/s = 70 × 18/5 kmph = 252kmph
The length of the diagonal of a rectangle is 26 cm, and one side is 10 cm. The area of the rectangle is:
The perimeters of two similar triangles, ∆ PQR and ∆ XYZ are 48 cm and 24 cm respectively. If XY = 12 cm. then PQ is:
If the area of a square field is 625 m2, then find the diagonal of the square field.
A room 20 m long, 16 m broad and 8m high has 2 windows of 1 m and `1(1)/(2)` m and a door of 2m`xx` `1(1)/(2)` m. Find the cost of paper...
The radius of a circle is equal to the radius of base of a cone. If the diameter of the circle is 35 cm and the height of cone is 18 cm, then find the v...
Area of a rectangle is equal to the total surface area of a hemisphere having volume 8192 cm³. Find the perimeter of the rectangle if its length is 125...
Outer diameter of 20 cm long pipe is 25 cm. If the thickness of the metal in the pipe is 1 cm. Find the total surface area of the pipe?
A sum of Rs. 15979 was divided between Wasim and Simran in such a way that if both invested their shares at 5 percent compound interest per annum. the ...
If the Ratio of the cuboid of the length, breath and height is 2:3:5. If length, breadth and height is increased by 25%, 10%, 30% respectively then find...
The perimeter of a rectangle is 130% more than perimeter of a square of side 10 cm. If the length of rectangle is 250% more than side of square then fin...