1. In a Chinese restaurant the menu list 8 items in column A and 6 items in column B.
a. To order a dinner, the diner is told to select 3 items from column A and 2 from column B. How many dinners are possible?
b. How many dinners are possible if the diner can select up to 3 from column A and up to 2 from column B? Assume at least one item must be included from either A or B.
(1 from A) AND (1 from B) OR (1 from A) AND (2 from B) OR
(2 from A) AND (1 from B) OR (2 from A) AND (2 from B) OR
(3 from A) AND (1 from B) OR (3 from A) AND (2 from B)
+
+
=
=
2. The average resident of a certain East Coast suburb spends 42 minutes per day commuting, with a standard deviation of 12 minutes. Assume a normal distribution. Find the percent of all residents of this suburb who have no more than 35 minutes per day commuting time.
To do this on a TI-83 or 84 calculator:
Press these:
2nd
VARS
2
You see normalcdf(
Press
-1
2nd
COMMA
99
COMMA
35
COMMA
42
COMMA
12
)
You should see this normalcdf(-1E99,35,42,12)
ENTER
Read 0.2798344168 or about 28%.
--------------------------------------
If you do it with a normal table, it will only
be accurate to the nearest nundredth, so you can
only hope to get the above rounded to hundredths, or
0.28 or 28% if you use a table.
calculate the z-score
What you do next depends on what type of normal table
you have in your book.
If you have the type which has negative z-scores, just
look up -0.5 in the z-column, then go across to .08 at
the top and read 0.2810, then round to 0.28
If you have the type which has only positive z-scores, just
look up 0.5 in the z-column, then go across to .08 at
the top and read 0.2190. Then subtract 0.5 - 0.2190 = 0.2810
which rounds to 0.28, or 28%.
Edwin
