In a certain assembly, 90% of all of the weld failures occur in the weld metal itself, and the remaining 10% occur in the base metal. When a weld failure occurs in the base metal, the corresponding section needs to be repaired thoroughly. Assume that the type of failure of a weld occurs independently of the types of failures of other welds. A sample of 50 weld failures is examined. a) How many of these failures would you expect to occur in the base metal? b) What is the standard deviation of the number of failures needing thorough repairs? c) What is the probability that fewer than six of these weld failures need thorough repairs? d) Of the next three batches of 50 weld failures inspected, what is the probability that only one of the batches will contain sections requiring thorough repairs
In a certain assembly, 90% of all of the weld failures occur in the weld metal itself, and the
remaining 10% occur in the base metal. When a weld failure occurs in the base metal, the
corresponding section needs to be repaired thoroughly. Assume that the type of failure of a
weld occurs independently of the types of failures of other welds. A sample of 50 weld failures
is examined.
a) How many of these failures would you expect to occur in the base metal?
b) What is the standard deviation of the number of failures needing thorough repairs?
c) What is the probability that fewer than six of these weld failures need thorough repairs?
d) Of the next three batches of 50 weld failures inspected, what is the probability that only
one of the batches will contain sections requiring thorough repairs?
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