ASHLY DEL ROSARIO
11 – ARCHIMEDES
STATS LAS 7-8
LET US PRACTICE
1. If a canned good is selected, what is the probability that the cholesterol content
will be greater than 220 milligrams?
P (X > 220) = 1 – P (X ≤ 220)
= 1 – P (Z
≤
220−215
15
√1
)
= 1 – P (Z ≤ 0.33333)
= 0.3694
2. If a sample of 25 canned goods is selected, what is the probability that the mean
of the sample will be larger than 220 milligrams?
P (X > 220) = 1 − P (X ≤ 220)
= 1 – P (Z
≤
220−215
15
√25
= 1 – P (Z ≤ 1.66667)
= 0.0478
)
LET US PRACTICE MORE
The average public high school has 468 students with a standard deviation of 87.
1) If a public school is selected, what is the probability that the number of students
enrolled is greater than 400?
Z=
(400−468)
87
= - 0.7816
0.217
= 1 – 0.217
= 0.783
2) If a random variable of 38 public elementary schools is selected, what is the
probability that the number of students is between 445 and 485?
σ
√
=
n
=
=
87
√38
= 14.11
445−468
14.11
485−468
14.11
= -1.63
= 1.20
(445 ≤ X ≤ 485) = 0.8849 − 0.0516
= 𝟎. 𝟖𝟑𝟑𝟑 𝐨𝐫 𝟖𝟑. 𝟑𝟑%
EVALUATION
1) C
2) A
3) A
4) B
5) D
6) C
7) C
8) A
9) C
10) A