Let $y_1, y_2, y_3, \dots, y_n$ be $n$ observations. Let $w_i = l y_i + k$ for all $i = 1, 2, 3, \dots, n$,where $l$ and $k$ are constants. If the mean of $y_i$ is $48$ and their standard deviation is $12$,and the mean of $w_i$ is $55$ and their standard deviation is $15$,then the values of $l$ and $k$ are:

• A
  $l = 2.5, k = 5$
• B
  $l = 1.25, k = 5$
• C
  $l = 1.25, k = -5$
• D
  $l = 2.5, k = -5$