(Solved): Determine the mean and variance of the random variable with the following probability mass function ...

Determine the mean and variance of the random variable with the following probability mass function. \[ f(x)=(343 / 57)(1 / 7)^{x}, x=1,2,3 \text {. } \] Round your answers to three decimal places (eg. 98.765). Mean \( = \) Variance = Attempts:0 Using multiple attempts will impact your score. \( 5 \% 6 \) score reduction after attempt 3