288 MODERN BUTTER MAKING. 



70. Knowing the acidity of both cream and starter 

 find the acidity after starter is added to cream. 



Problem: The acidity of the starter is .70%; the 

 acidity of the cream (100 lbs.) is .22%. 30% (or 30 

 lbs.) of starter is added to every 100 lbs. of cream. 

 Find acidity of cream after starter is added. 



Rule: To the acidity in the cream add the acidity 

 in the per cent of starter (30 lbs.) to be added, and 

 divide the sum by 100 + the per cent to be added. 

 Multiply the quotient by 100 and the result will be 

 the acidity of cream after starter is added. 



Solution : (70X30)-^100=.21 ; .21 + .22 = .43 ; 

 .43-^130—0033; .0033X100=.33%. Ans, 



Explanation: 100 lbs. cream tests .22% acidity. 

 100 lbs. starter tests .70%. We add 30% or 30 lbs. 

 of starter to each 100 lbs. of cream. We have .22% 

 acidity in each 100 lbs. cream. We have 30 lbs. of 

 starter at .70% acidity=.21 acidity. The total acidi- 

 ty is .43. The total cream and starter is 130 lbs. 

 and the total acidity of cream and starter is .43; 

 .43-=-130— 0033. .0033X100=.33%, the acidity of 

 100 lbs. of cream after the starter is added. 



Problems for Practice. 



Find acidity of cream when the per cent of 

 starter to be added is : 



