Subject

Mathematics

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsLong Answer Type

31.

Using integration, find the area of the region bounded by the triangle whose vertices are (-1, 2), (1, 5) and (3, 4).

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32.

A manufacturing company makes two types of teaching aids A and B of Mathematics for class XII. Each type of A requires 9 labour hours of fabricating and 1 labour hour for finishing. Each type of B requires 12 labour hours for fabricating and 3 labour hours for finishing. For fabricating and finishing, the maximum labour hours available per week are 180 and 30 respectively. The company makes a profit of 80 on each piece of type A and 120 on each piece of type B. How many pieces of type A and type B should be manufactured per week to get a maximum profit? Make it as an LPP and solve graphically. What is the maximum profit per week?


Let x be the number of pieces manufactured of type A and y be the number of pieces manufactured of type B. Let us summarize the data given in the problem as follows:

Product Time for Fabricating (in hours) Time for Finishing (in hours) Maximum labour hours available
Type A 9 1 180
Type B 12 3 30
Maximum Profit (in Rupees) 80 120  

Thus, the mathematical form of above LPP is
Maximize Z = 80x+120y
subject to
9 straight x plus 12 straight y less or equal than 180
straight x plus 3 straight y less or equal than 30
Also, we have straight x greater or equal than 0 comma space space straight y greater or equal than 0
Let us now find the feasible region, which is the set of all points whose coordinates satisfy all constraints. 
Consider the following figure. 


Thus, the feasible region consists of the points A, B and C.
The values of the objective function at the corner points are given below in the following table:
Points Value of Z
A(12, 6) Z = 80 x 12 + 120 x 6 = Rs. 1680
B(0, 10) Z = 80 x 0 +120 x 10 = Rs. 1200
C(20, 0) Z = 80 x 20 + 120 x 0 = Rs.1600

Clearly,Z is maximum at x=12 and y=6 and the maximum profit is Rs.1680.
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33.

There are three coins. One is a two-headed coin (having head on both faces), another is a biased coin that comes up heads 75% of the times and third is also a biased coin that comes up tails 40% of the times. One of The three coins is chosen at random and tossed, and it shows heads. What is the probability that it was the two-headed coin?

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34.

Two numbers are selected at random (without replacement) from the first six positive integers. Let X denote the larger of the two numbers obtained. Find the probability distribution of the random variable X, and hence find the mean of the distribution.

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35.

Evaluate:
integral fraction numerator 1 over denominator sin to the power of 4 straight x plus sin squared xcos squared straight x plus cos to the power of 4 straight x end fraction dx

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