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I need someone to help me solve this math problem

answer is 13.83years..
I will post the explanations later.. my battery is flat now

monsieurbanky:
I need someone to help me solve this math problem

dejt4u:
answer is 13.83years..

I will post the explanations later.. my battery is flat now

step 1: Calculate the sum of the ages of the 25 pupils
= number of pupils x average age
= 25 x 14
= 350 years

step 2: Calculate the sum of the ages of the 7 pupils that left
= number of pupils x average age
= 7 x 12
= 84 years

step 3: Calculate the sum of the ages of the remaining 18 pupils
= sum of the ages of the 25 pupils - sum of the ages of the 7 pupils that left
= 350 - 84
= 266 years.

step 4: Calculate the sum of the ages of the 6 new pupils that joined
= number of pupils x average age
= 6 x 11
= 66 years

step 5: add the 66 years above to the ages of the remaining 18 pupils
= 66 + 266
= 332 years.

NOTE: we now have 6 + 18 pupils in the class = 24 pupils

step 6: Calculate the new average age
average age = sum of ages/number of pupils
average age = 332/24
average age = 13.83 years or 13r5/6 or 13years 10months.

the answer at the back box the textbook is actually 14 years.thanks any way for attempted the questions