The average weight of a sac of wheat in a truck is reduced by 0.2 lbs from 50 lbs when 5 new sacs, each weighing 47.4 lbs on an average, are loaded. How many sacs did the truck originally carried?
The Usual Method
Let there be ‘x’ number of sacs in the truck originally.
Hence total weight of the load in the truck = 50x
New number of sacs = x + 5
New average weight = = (49.8x + 249) lbs
Total weight of new sacs = 47.4 x 5 = 237 lbs
Hence 49.8x + 249 = 50x + 237
Estimated Time to arrive at the answer = 60 seconds.
Difference between the average weight of the original sacs and the new sacs = 50 – 47.4 = 2.6lbs
Total difference = 2.6 x 5 = 13 lbs. Now this 13 lbs is reduced from the total weight of (x + 5) bags and the reduction is that of 0.2 lb each. Hence
Estimated Time to arrive at the answer = 15 seconds.