If the coefficient of real expansion  γR is 1% more then coefficient of apparent expansion, linear expansion coefficient of the material is

given γR coefficient of real expansion in 1% more than γa coefficient of apparent expansion ⇒γR=γa+1100γa=101100γa we know that  γR=γa+γg γR=γa+3αg substitute γavalue here γR=100101γR+3αg 3αg=γR1−100101=γR101 αg=γR303