Determine probability the y is within 1 standard deviation

Air tickets sold : 5S Available Seats = 50 y = # pass who show up for flight omf y p( x ) 45 10.03 46 0. 08 47 0 . 1 2 48 014 49 0. 28 50 0 . 17 51 0. 07 52 0. 05 53 0103 154 0. 02 155 2.01 Sum 1.00 E ( y ) = 49,000 V (y ) : 4, 060 Determine prob that y is w/ in standard dev. of its mean value