SELECT sum(T2.hours) FROM assignedto AS T1 JOIN projects AS T2 ON T1.project  =  T2.code JOIN scientists AS T3 ON T1.scientist  =  T3.SSN WHERE T3.name  =  'Michael Rogers' OR T3.name  =  'Carol Smith'
What is the sum of hours for projects that scientists with the name Michael Rogers or Carol Smith are assigned to?
SELECT sum ( T2.hours ) FROM assignedto AS T1 JOIN projects AS T2 ON T1.project = T2.code JOIN scientists AS T3 ON T1.scientist = T3.SSN WHERE T3.name = 'Michael Rogers ' OR T3.name = 'Carol Smith '
select sum ( t2 . hours ) from assignedto as t1 join projects as t2 on t1 . project = t2 . code join scientists as t3 on t1 . scientist = t3 . ssn where t3 . name = value or t3 . name = value
What is the sum of hours for projects that scientists with the name Michael Rogers or Carol Smith are assigned to ?