Board Paper of Class 12-Science 2004 Maths Delhi(SET 1) - Solutions

If , then show that the vectors and are orthogonal.

Or

Find x such that the four points A(3, 2, 1), B(4, x, 5), C(4, 2, −2), and D(6, 5, − 1) are coplanar.

Prove that:

Find the Cartesian and vector equations of a line, which passes through the point (1, 2, 3) and is parallel to the line

Find the Cartesian equation of the sphere which has the points A (2, −3, 4) and B (−5, 6, −7) as the end points of one of its diameters. Also find its centre and radius.

Out of current syllabus
 

Show that the lines and intersect. Find the point of intersection also.

Three forces acting on a point are in equilibrium. If the angle between be double the angle between , prove that

Out of current syllabus

Two unlike parallel forces act at two points units apart. Show that if the direction of be reversed, the resultant will be displaced by a distance units. 

Out of current syllabus

A particle starting with some initial velocity and moving with uniform acceleration acquires a velocity of 20 cm/sec after moving through 10 cm from a point P to Q and a velocity of 30 cm/sec after further moving 20 cm from Q to R in the same direction. Find
(i) its velocity at the point P
(ii) its acceleration
(iii) the time it will take and the distance

Out of current syllabus

OR

From a point on the ground at a distance from the foot of a vertical wall, a ball is thrown at an angle of 450 which just clears the top of the wall and afterwards strikes the ground at a distance of yon the other side of the wall. Find the height of the wall.

Out of current syllabus

Find the banker's discount and true discount on a bill of Rs 22,800 due 4 months at 4% per annum.

Out of current syllabus

A bill of exchange drawn on January 4, 2003 at 5 months date was discounted on march 26, 2003 at 3% per annum. If the banker's discount is Rs 1207.20, find the face value of the bill.

Out of current syllabus
 

Three urns A, B, and C contain 6 red and 4 white, 2 red and 6 white, and 1 red and 5 white balls respectively. An urn is chosen at random and a ball is drawn. If the ball drawn is found to be red, find the probability that the ball was drawn from urn A.

The mean and variance of a binomial distribution are 4 and respectively. Find P(X ≥1).

OR

If the sum of the mean and variance of a binomial distribution for 5 trials be 1.8, find the distribution.

A, B, and C are partners in a business. A, being a working partner, receives 10% of the total profit as salary. The remaining profit is distributed among them in the ratio of 2 : 3 : 4. If A gets Rs 3,00,000 in all, find the shares of B and C.

Out of current syllabus
 

Find the present value of an annuity of Rs 1,200 payable at the end of each of the 6 months for 3 years, when the interest is 8% per annum, compounded semi-annually. 

[Use (1.04)⁶= 1.2653]

The total cost and demand function of an item are given by

and p = 100 − xrespectively.
Write the total revenue function and the profit function. Find the number of items when the profit will be maximum. Find the maximum profit also.

An oil company requires 13,000, 20,000 and 15,000 barrels of high grade, medium grade and low grade oil respectively. Refinery A produces 100, 300 and 200 barrels per day of high, medium and low grade oil respectively whereas refinery B produces 200, 400 and 100 barrels per day respectively. If A costs Rs 400 per day and B costs Rs 300 per day to operate, how many days should each be run to minimize the cost of requirement?

OR

A firm makes items A and B and the total number of items it can make in a day is 24. It takes one hour to make an item of A and only half an hour to make an item of B. The maximum time available per day is 16 hours. The profit on an item of A is Rs 300 and on one item of B is Rs 160. How many items of each type should be produced to maximize the profit? Solve the problem graphically.