Question 89314

  2. Suppose g varies inversely as w, and when w is 8, g is 37. What is g when w is 5.2? 
3. The illumination from a light source varies inversely as the square of its distance from the light source. 
a. Explain what this means specifically.
b. What is the change in illumination of a lamp you moved from 10 to 15 inches from a table?

   2) g varies inversely as w   i.e, g = k/w where k is a proportionality 

        constant. 
                                     g = k/w   

              when w = 8 , g = 37  or k = g*w = 8*37 = 296
              when w = 5.2 g =?    or g = k/w = 296/5.2 = 2960/52 = 56.92
 
    3)a) As the distance of the light source increases illumination decreases.

      b)When distance d = 10 inch  i = k/100    or k = 100*i
           When D = 15 inch    I = k/15*15 = k/225

                               I = 100i/225 = (4/9)i

     Hence illumination at 15 inch will be 4/9  times illumination at 10 inch.