In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:
Assertion (A) : The mean weight of \(6\) students is \(35 \ kg\). If one more student is joined in the group the mean is unaltered, then the weight of the \(7^{th}\) student is \(35 \ kg\).
Reason (R) : The mean of \(x\), \(y\) and \(z\) is \(y\), then \(x + z = 2y\)