Answer: C.156
Step-by-step explanation:
Given: Total seashells = 160
mean = 120
population standard deviation = 26 grams
The probability that the seashells weigh at least 68 grams :-'
[tex]P(X\geq68) =P(\dfrac{x-\mu}{\sigma}\geq\dfrac{68-120}{26})\\\\=P(z\geq-2)\\\\=P(z<2)\ \ \ [P(Z\geq-z)=P(Z<z)]\\\\= 0.9772\ \ \ [\text{By p-value table}][/tex]
Total seashells weigh at least 68 grams = 0.9772 x 160 = 156.352≈ 156
Hence, the correct option is C.156
