MEDIUM
Earn 100

Which mode of transport is the cheapest for transporting goods?

50% studentsanswered this correctly

Important Questions on Application of Derivatives

HARD
Find two positive numbers whose sum is 15 and the sum of whose squares is minimum.
HARD

A tank with rectangular base and rectangular sides, open at the top is to be constructed so that its depth is 2 m and volume is 8 m3. If building of tank costs  70 per square metre for the base and  45 per square metre for the sides, what is the cost of least expensive tank?

EASY
Show that the height of the right circular cylinder of greatest volume which can be inscribed in a right circular cone of height h and radius r is one-third of the height of the cone, and the greatest volume of the cylinder is 49 times the volume of the cone.
MEDIUM
A spherical iron ball of radius 10 cm is coated with a layer of ice of uniform thickness that melts at a rate of 50 cm3/min. When the thickness of the ice is 5 cm, then the rate at which the thickness (in cm/min) of the ice decreases, is :
HARD
The point on the curve x2=2y which is nearest to the point 0,5 is
HARD
A water tank has the shape of an inverted right circular cone, whose semi-vertical angle is tan-112. Water is poured into it at a constant rate of 5 cubic m/min. Then the rate (in m/min), at which the level of water is rising at the instant when the depth of water in the tank is 10 m; is:
HARD
An open tank with a square base and vertical sides is to be constructed from a metal sheet so as to hold a given quantity of water. Show that the cost of material will be least when depth of the tank is half of its width. If the cost is to be borne by nearby settled lower income families, for whom water will be provided, what kind of value is hidden in this question ?
MEDIUM

Find the rate of change of the area of a circle with respect to its radius r when r = 3 cm

MEDIUM
If S1 and S2 are respectively the sets of local minimum and local maximum points of the function, fx=9x4+12x3-36x2+25,xR, then
HARD
If f(x) is a non-zero polynomial of degree four, having local extreme points at x= 1, 0, 1; then the set S={xR :fx=f0} contains exactly
EASY
A 2m ladder leans against a vertical wall. If the top of the ladder begins to slide down the wall at the rate 25cm/sec , then the rate (in cm/sec.) at which the bottom of the ladder slides away from the wall on the horizontal ground when the top of the ladder is 1 m above the ground is:
MEDIUM
From the top of a 64 metres high tower, a stone is thrown upwards vertically with the velocity of 48 m/s. The greatest height (in metres) attained by the stone, assuming the value of the gravitational acceleration g=32 m/s2, is:
MEDIUM
The total cost Cx associated with the production of x units of an item is given by C(x)=0·005x3-0·02x2+30x+5000. Find the marginal cost when 3 units are produced, where by marginal cost we mean the instantaneous rate of change of total cost at any level of output.
EASY
The radius of a circle is increasing at the uniform rate of 3 cm/sec. At the instant when the radius of the circle is 2 cm, its area increases at the rate of kπ cm2, then k=_____
MEDIUM
 Find the rate of change of the area of a circle with respect to its radius r at r = 6 cm. 
MEDIUM
The total revenue in Rupees received from the sale of 'x' units of a product is given by Rx=3x2+36x+5. The marginal revenue, when x=15 is
HARD
Suppose fx is a polynomial of degree four having critical points at -1, 0, 1. If T=xR |fx=f0, then the sum of squares of all the elements of T is :
EASY
Let M and m be respectively the absolute maximum and the absolute minimum values of the function, fx=2x3-9x2+12x+5 in the interval [0,3] . Then M-m is equal to
HARD
If the function f given by fx=x3-3a-2x2+3ax+7, for some aR is increasing in 0, 1 and decreasing in 1, 5, then a root of the equation, fx-14x-12=0, x1 is :