Question
Average of 20 numbers is 90. Average of first 8 numbers
is 114 while average of last nine numbers is 40. If ninth number is 25% less than the tenth number which is equal to the eleventh numbers then find the tenth number.Solution
Sum of ninth, tenth and eleventh number = 20 × 90 – 8 × 114 – 9 × 40 = 528 Let tenth number = x = eleventh number So, ninth number = 0.75 × x = 0.75x So, x + 0.75x + x = 528 Or, 2.75x = 528 Or, x = 192
The ratio of the total distance traveled by a body to the total time taken is its:
A concave mirror forms a real, inverted image of an object placed beyond its focus. What happens if the object is moved closer to the mirror but still b...
In which type of wave do the particles of the medium vibrate perpendicular to the direction of wave propagation?
The half-life of a radioactive substance is 10 days. The time in which only 1/8th of the original substance remains is:
A body moves with uniform acceleration and covers 80 m in 4 s and 160 m in next 4 s. Find initial velocity.
Which property of a wave is related to its frequency?
Which of the following decays does not change the atomic number of the nucleus?
A meter stick moves along its length with a certain speed. The apparent length of the moving meter stick as measured by a stationary observer on the gr...
Water flows through a horizontal pipe at a constant volumetric rate. At a location where the cross sectional area decreases, the velocity of the fluid:
Which law is violated if two bodies in mutual gravitational interaction exert unequal forces on each other?
