Find the sample variance and standard deviation for the data set: 23, 13, 3, 7, 12.
a) Variance: 45.2; Standard deviation: 6.7
b) Variance: 48.8; Standard deviation: 7.0
c) Variance: 53.2; Standard deviation: 7.3
d) Variance: 57.6; Standard deviation: 7.6