The expected value of the inseam length of the jeans is found as
30% of 30+ 25% of 32+ 10% of 34+ 10% of 36 + 10% of 38 + 15% of 40
= [tex]\frac{30}{100}\times30 +\frac{25}{100}\times32+ \frac{10}{100}\times34+ \frac{10}{100}\times36 +\frac{10}{100}\times38+ \frac{15}{100}\times40[/tex]
= [tex]9+8+3.4+3.6+3.8+6=33.8[/tex]
Hence, the third option 33.8 is the correct expected value.