Transcript Lesson 12: Continuity Correction

STARTER
In a Stats test the mean was 54% and the
standard deviation was 18%. The marks were
normally distributed.
Find the probability that a student selected at
random got over 75%
P(X > 75) = 0.12167
Find the probability a student got a mark
between 49 and 62?
P(49 < X < 62) = 0.28105
Note 15: Continuity Correction
The normal distribution is often used
to approximate discrete variables.
This occurs when data is measured to
the nearest whole number value. To
find the cut off point for continuity
correction, move up or down to the
midpoint between whole number
values.
Example: Weights of punnets of
strawberries are normally distributed with a
mean of 250g and a standard deviation of
10g. If they are measured to the nearest
gram calculate the probability that the
weight of the punnet of strawberries is
greater than 265g.
P(X > 265) = P(X > 265.5)
= 0.06057
250
265.5
Lower
265.5
Upper
10000

10

250
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Exercise I