446 MANUAL OF MILK PRODUCTS 



desired. Place at the left-hand corners of the rectangle the percentages 

 of fat in the materials to be mixed. Subtract the number in the center 

 from the larger number at the left of the rectangle. Place the re- 

 mainder on the diagonally opposite right-hand corner of the rectangle. 

 Subtract the smaller number on the left-hand corner from the number 

 in the center and place the remainder on the diagonally opposite right- 

 hand corner of the rectangle. 



The two numbers on the right-hand corners of the rectangle represent 

 the number of pounds of material required. If these two numbers are 

 added they will express the number of pounds of the mixture, which will 

 contain a percentage of fat expressed by the number in the center of the 

 rectangle. In each case the number on the right-hand corner corre- 

 sponds in fat test to the number on the left-hand corner directly opposite. 



Problem 8 



How many pounds of 40 per cent cream and 3 per cent milk must be 

 mixed to make milk testing 5 per cent? Using the diagram as de- 

 scribed, the following result is obtained : 



This means that if 2 lb. of 40% cream are mixed with 35 lb. of 3% 

 milk, the result will be a 37-lb. mixture testing 5%. Answer. 



Problem 9 



How many pounds of 28 per cent cream and 3 per cent milk will be 

 required to make 500 lb. of a mixture testing 4 per cent? In this 

 problem a definite number of pounds of the mixture is required. 

 According to the conditions of the problem there would be 500 lb. of 4% 

 milk. This amount of milk would contain 20 lb. of fat (500 X.04 = 20). 

 According to the results the 500 lb. would be made up of 480 lb. of 3% 

 milk and 20 lb. of 28% cream. The 480 lb. of 3% milk would contain 

 14.4 lb. of fat (480 X .03 = 14.4). The 20 lb. of 28% cream would 

 contain 5.6 lb. of fat (20 X .28 = 5.6). 



14.4 + 5.6 = 20 



Since the 500 lb. contain 20 lb. of fat, and the materials of which the 

 500 lb. is made up furnish the 20 lb. of fat, the problem is worked cor- 

 rectly. 



Problem 10 



How many pounds of 3 per cent milk must be mixed with 150 lb. 

 of 28 per cent cream to make a mixture testing 4 per cent ? In this 

 problem the number of pounds to be made up is not definitely known. 



Working the problem by the rectangle method, 1 part of 28% cream 

 is required for 24 parts of 3% milk. According to the terms of the 

 problem, 150 lb, of 28% cream must be used, and this is 150 times as 



