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Warm-up 8.3 and 8.4 C.I.and Inference Test of two Ind. Proportions. 1. Consider two events: E and F . We know that P ( E ) = P ( F ) = 0.7. Are the two events E and F disjoint? A) Yes. B) No, because P ( E ) and P ( F ) are equal.
1. Consider two events: E and F. We know that P(E) = P(F) = 0.7.
Are the two events E and F disjoint?
A) Yes. B) No, because P(E) and P(F) are equal.
C) No, because P(E and F) is unknown.
D) No, because P(E) and P(F) add up to more than 1.
2. Suppose Lynn rolls a fair die until a six appears on top.
What is the probability that it will take Lynn more than two
rolls to get a six the first time?
A) B) C)
Same as one proportion, except slightly different formulas
and one more condition.
Confidence interval for a population difference in proportions
On Calculator: STAT -> TESTS -> 2 PropZInt.
Extra condition: Plausible Independence Condition – It is
important to be certain the sample groups are independent
of each other AND success/failure condition (must be at least 5 in
A recent study of 1000 randomly chosen residents in each of two
randomly selected states indicated that the percent of people living in
those states who were born in foreign countries was 6.5% for State A
and 1.7% for State B. Find a 99% confidence interval for the difference
between the proportions of foreign born residents for these two states.
Seatbelt was recorded at 161 locations in Masachusettes,
using a random-sampling methods by the National Highway
Traffic Safety Administration. Of 4208 male drivers with
female passengers , 2777 (66.0%) were belted. But among
2763 male drivers with male passengers only, 1363 (49.3%)
Complete a significance test to determine if there is a
difference in proportions between male drivers who wear
seatbelts when sitting with male passenger and the
proportion who wear seatbelts when sitting next to
Because the conditions are satisfied, I’ll use a Normal model
and perform a two-proportion z-test.
Step 2 : State the hypotheses.
Ho: There is no difference between
the proportion of males wearing
seatbelts with female passengers and the proportion of
males wearing seatbelts with male passengers.
HA: There is a difference between the proportion of males
wearing seatbelts with female passengers and the proportion
of males wearing seatbelts with male passengers.
Step 3 : STAT-> TESTS - > 2-PropZTest
Write z-score (test statistic), p-value, make a picture
Step 4: Write a conclusion.
Next block Notebook Check
10.1, 10.2, 10.3, Ch. 11 Day 1, Ch. 11 Day 2, 8.3&8.4, 9.3 &9.4
7 notes with warm-ups – must be completed for credit!
7 x 14 points = 98 pts