(1 - y)12 represents the price of the set of tennis balls after a coupon was applied.
45th percentile means that 45% of the data fall below that number while 55% (that is, 100-45) fall above it.
Now, arranging the number in ascending order;
$60, $85, $95, $105, $120, $145, $155, $175, $190, $215, $235, $240, $260, $285, $325
The total number of counts = 15
Then,
Index = 15*45% = 15*0.45 = 6.75
Round up,
Index = 7
The,
7th number = $155
Therefore, 45th percentile value of the data = $155
