apex to calculate the average code example

Example: apex to calculate the average

(IF(ISNULL(Base_Q1__c),0,Base_Q1__c) + IF(ISNULL(Base_Q2__c),0,Base_Q2__c)+IF(ISNULL(Base_Q3__c),0,Base_Q3__c) +IF(ISNULL(Base_Q4__c),0,Base_Q4__c))
/
(IF(ISNULL(Base_Q1__c),0,1) + IF(ISNULL(Base_Q2__c),0,1)+IF(ISNULL(Base_Q3__c),0,1) + IF(ISNULL(Base_Q4__c),0,1)