Question

please find out answer

Answer 1

Hey Friend, Harish here.

Here is your answer.

3) The first four odd numbers are 1,3,5,7

Their average = sum of all numbers / total numbers

Sum of all numbers = 1+ 3+5+7= 16

Total numbers = 4

∴ Average= 16/ 4 = 4

Option B is the correct answer.

4) The average = sum of all numbers/ total numbers

Sum of first 10 natural numbers = n(n+1)/2   (where n =10 0
                                                   = 10 x 11 / 2
                                                   = 5 x 11 
                                                   = 55

Total numbers = 10

∴ Average of them = 55 / 10 
                               = 5.5

Option D is the correct answer

5) Let sum of salaries of 20 workers be x

Then their average of salary = Sum of their salaries/ Total number of people

                                Rs 1900= x/ 20
                              1900 x 20= x

Therefore sum of salaries of all workers = x = 1900 x 20 = Rs 38,000

Now assume managers salary to be y.

Then new average = sum of salaries of all / Total no. of people

Sum of salaries of all = Rs 38,000 +y 

Total people = 20 + 1 = 21   ( 20 workers & 1 manager)

 ∴ Their average = Rs 38,000 +y / 21
  
                   2000= 38,000 +y / 21
          2000 x 21 = 38000 +y
                42,000 = 38000 + y 

∴ y = 42,000 - 38,000 
      
      = Rs 4000.   

4000 is the monthly salary of the manager.

∴ Annual salary = 4000 x 12    ( because 12 months in a year)
                          = Rs 48,000

Option D is correct.

6) Let salary of  A = x
     "      "       "    B = y
     "      "       "    C = z

Then,
Average salary of A and B = Sum of their salaries / 2
                                                  
                                    1200= x+y / 2  -(i)

Average salary of B and C =   Sum of their salaries / 2
                                                  
                                     800 = (y+z)/ 2 - (ii)
 
Average salary of C and A  =Sum of their salaries / 2
                 
                                    1000 =(z+x)/2   - (iii)

Now add the equation (i) , (ii) , (iii)


We get  2( x+y+z) /2  = 1000 + 1200 +800 

               x + y + z  = 3000   - (iv)

We need to find y.

So In the (iii) equation we know tht :  1000 =(z+x)/2

Therefore (z + x ) =  1000 x 2 
                         
                            = 2000


Now substitute this value in equation (iv) ;

We get ;  (x + z )+ y  = 3000

                2000 +y = 3000

Therefore y = Rs 1000 

Therefore B's salary is 1000.

Option A is correct.

Hope my answer is helpful to u.