A boy was asked to find the L.C.M. of 3, 5, 12, and another number. But while calculating, he wrote 21 instead of 12 and yet came with the correct answer. ... We will assume the fourth number to be x. First, we will write down the given numbers as a product of their prime factors.

Find the L.C.M. of the following numbers in which one number is the factor of the other : 12,48 What do you observe in the results obtained.

Find the L.C.M. of the following numbers in which one number is always a multiple of 3: 12 and 5. Observe a common property in the obtained L.C.M.s. Is L.C.M. the product of two numbers in each case ?Is L.C.M. always a multiple of 3 ?

Find the L.C.M. of the following numbers in which one number is always a multiple of 3: 6 and 5. Observe a common property in the obtained L.C.M.s. Is L.C.M. the product of two numbers in each case ?Is L.C.M. always a multiple of 3 ?

Direction. In the following questions, a statement of assertion is followed by a statement of reason. While answering a question, you are required to choose the correct are out of the given four responses and mark it as (A). If both assertion and reason are true and reason is the correct explanation of the assertion, (B) if both assertion and reason are true but reason is not correct explanation of the assertion. (C) if assertion is true, but reason if false, (D) if both assertion and reason are false Assertion : We use a thick wire in the secondary of a step down transformer to reduce the production of heat. Reason : When the plane of the armature is parallel to the lines of force of magnetic field, the magnitude of induced e.m.f. is maximum.

5 people of a locality were asked about the time they spent in a week in doing social work. They told the number of hous as: x,x+3,x+6,x+7,x+4. find the mean number of devoted by first three members. If mean number of hours of 5 persons is 11 hours, what values do we draw from above data?

There is another useful system of units, besides the SI/MKS. A system, called the cgs system. In this system Coulumb's law is given by vecF = (Qq)/(r^2) hatr where the distance r is measured in cm (=10^(-2) m) , F in dynes (= 10^(-5) N) and the charges in electrostatic units (es units), where 1es unit of charge = 1/[3] xx 10^(-9) C . The number [3] actually arises the speed of light in vacuum which now taken to be exactly given by c = 2.99792458 xx 10^8 m/s . An approximate value of c then is c = [3] xx 10^8 m/s . Show that the Coulomb law in cgs units yields. 1 esu of charge = 1 (dy )^(1/2) cm . obtain the dimension of units of charge in terms of mass M, length L and time T. show that it is given in terms of fractional powers of M and L.

H.C.F. of co-prime numbers 4 and 15 was found as follows:factorisation : 4=2xx 2 and 15= 3 xx 5 .since there is no common prime factor,so H.C.F. of 4 anb 15 is 0.Is the answer correct?If not,what is the correct H.C.F ?

The total revenue in Rupees received from the sale of x units of a product is given by R(x) - 3x^2 +36x +5 Find the marginal revenue, when x = 5, where by marginal revenue we mean the rate of change of total revenue with respect to the number of items sold at an instant.

A conductor with a cross-section of 10^-4m^2 carries an electric current of 1.2 A. If the number of the free electrons are 5xx10^28m^-3 , calculate the electron drift velocity. Charge on the electron, e = 1.6 xx 10^-19C

The total revenue in Rupees received from the sale of x units of a product is givne by R(x) = 3x^2 + 36 x + 5 . Find the marginal revenue, when x = 6, where by marginal revenue we mean the rate of change of total revenue with respect to the number of items sold at an instant.