Quality Control Is an Important Issue at ACME Company, Which

Quality control is an important issue at ACME Company, which manufactures light bulbs. To test the life-hours of their light bulbs, they randomly sampled nine light bulbs and measured how many hours they lasted (mean = 346.6) . 378, 361, 350, 375, 200, 391, 375, 368, 321
What is the standard deviation?

A) 342.43
B) 3424.3
C) 58.5
D) 191
E) 10,609