Researchers at the University of Cambridge have been studying how brain shape is linked to cocaine addiction. They determined that sporadic cocaine users (non-addicts) tend to have a larger frontal...

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Extracted text: Researchers at the University of Cambridge have been studying how brain shape is linked to cocaine addiction. They determined that sporadic cocaine users (non-addicts) tend to have a larger frontal lobe (region associated with self-control) while cocaine addicts have a small frontal lobe. It was determined that a cocaine user with a small frontal lobe had a probability equal to 0.7 of becoming addicted to the drug. Researchers conducted a simple random sample of 20 independent cocaine users that had a small frontal lobe.


Extracted text: 20. On average, how many of the 20 cocaine users with a small frontal lobe would you expect to be addicted to cocaine?