A skating champion moves along the circumference of a circle of radius 28m in 44 sec. How many seconds will it take her to move along the perimeter of a hexagon of side 48 m ?
Answer: D Circumference of the circle = 2πr = 2* 22/7 * 28 = 176 m Given, side of the hexagon = 48m So, perimeter of the hexagon = 48*6 = 288m Skating champion moves 176 m in 44 sec Skating champion moves hexagon (288m) in 44/176 * 288 = 72 sec.
Q. No. 38:
The circumference of the front wheel of a cart is 40 ft long and that of the back wheel is 48 ft long. What is the distance travelled by the cart, when the front wheel has done five more revolutions than the rear wheel ?
Answer: C
Let the total distance travelled by the cart be x ft. Then, x/40 - x/48 = 5 => (6x-5x)/240 = 5 => x = 1200 ft.
Q. No. 39:
A hare pursued by a round is 30 m before the hound at starting. Whilst the hare takes 4 leaps the hound takes 3. In one leap the hare goes 3/2 and hound 5/2 m. How far will the hare have gone when the hound will catch the hare ?
Answer: B Let the hare take 4leaps/m/min and hound 3leaps/m/min. Speed of hare = 4 * 3/2 = 6 m/min. Speed of hound = 3* 5/2 = 15/2 m/min Initial distance = 30 m. Difference in speed = 3/2 m/min Now, Distance = speed * time => 30 = 3/2 * t => t = 20 min. Time taken by hound to catch hare in 20 min, hare traveled = 20*6 = 120 m.
Q. No. 40:
A man can row 6 km/hr in still water. If it takes him twice as long to row up, as to row down the river, then the rate of current in the stream would be :
Answer: B D= distance and x = speed of stream. Then, 2D/(6+x) = D/(6-x) => x = 2 km/hr.
Q. No. 41:
A car driver driving in fog, passes a pedestrian who was walking at the rate of 2km/h in the same direction. The pedestrian could see the car for 6 min and it was visible to him upto a distance of 0.6 km. The speed of the car would be :
Answer: A Traveller distance in 6 min = 2/60 * 6 = 2/10 km. Total distance in 6 min = 2/10 + 6/10 = 8/10 km. Speed = 8/10 * 10 = 8 km/hr.
Q. No. 42:
A boat goes 30km upstream and 44 km downstream in 10 hour. In 33 hr, it can go 40 km upstream and 55km downstream. The speed of the boat in still water is :
Answer: C Suppose 30 km upstream is covered in 3x hours and 40km upstream is covered in 4x hr. 44 km downstream is covered in 4y hours and 55 km downstream is covered in 5y hr. Then, 3x+4y = 10..........(i) 4x+5y = 13................(ii) On solving we get, x= 2 and y = 1 Upstream speed = 30km/3x = 5 km/hr Downstream speed = 44/4y = 11 km/hr Speed of boat = (11+5)/2 = 8 km/hr.