Question:The average age of `30`students is `9` years. If the age of thier teacher is inclued,it becomes `10` years .The age of the teacher (in years) is :
A `27`
B `3`
C `35`
D `40`
/54
+ Answer
D
+ ExplanationAge of the teacher
`= (31 xx 10 + 30 xx 9)`
`= 40 years`