Search & Filtering
Convert 16500 tonnes to kg/ha
Convert 37 (µmol/L) of sulphate to mg/l.
State whether the following statement true or false
QUESTION 4
The number of arrivals per minute at a bank located in the central business district of a large city
was recorded over a period of 200 minutes, with the following results:
Arrivals Frequency
0 14
1 31
2 47
3 41
4 29
5 21
6 10
7 5
8 2
The probability of at least two arrivals per minute at the bank is 0:155:
Unit conversion for Soluble Reactive Silica (SRSi)
- 25.5 μmol L-1 to (mg l-1)
- 0.82 (mg l-1) to μmol L-1
QUESTION 26
A local fire station receives on average 8.5 emergency telephone calls per hour. Assume that
these calls are Poisson distributed. Calculate the probability that
(a) the fire station will get nine calls during one hour. (2)
(b) the fire station will get five to seven (inclusive) calls during one hour. (3)
(c) the fire station will get at least 4 calls during one hour. (3)
(d) the fire station will get more than 6 calls during one hour.
QUESTION 25
Suppose that X is a binomial random variable with n D 25 and p D 0:5: Calculate
(a) the probability P .X D 15/: (2)
(b) the probability P .X 16/: (4)
(c) the expected value of X. (2)
(d) the variance of X. (3)
Unit conversion for Soluble Reactive Phosphorus (SRP PO4-P)
Convert the following:
- 9706.7 (mg/m2) to (μg 1-1)
- 6.4 (μg 1-1) to (mg/m2)
- 0.04 mg/l to (μg 1-1)
QUESTION 24
According to a report from the research for Studying Health System Change, 20% of South Africans
delay or go without medical care because of concerns about cost. Suppose that 8 individuals are
randomly selected.
(a) What is the probability that two individuals will delay or go without medical care? (2)
(b) What is the probability that at most two individuals will delay or go without medical care? (3)
(c) What is the probability that at least seven individuals will delay or go without medical care?
(3)
[8]
QUESTION 21
Let X represent the number of children in a randomly selected South African household. The
probability distribution of X is given below.
x 1 2 3 4 5
P .x/ 0:25 0:33 0:17 0:15 0:10
(a) What is the probability that a randomly selected South African household will have more than
2 children? (3)
(b) What is the probability that a randomly selected South African household will have between
2 and 4 children (inclusive)? (3)
(c) What is the probability that a randomly selected South African household will have fewer than
4 children? (3)
(d) Calculate the expected number of children in a randomly selected South African household.
(4)
(e) Calculate the variance of the number of children in a randomly selected South African house-
hold. (5)
[18]
A sample of oxygen gas (O
2
) has a volume of
9
.0 L and a pressure of
2
.0 atm. What is the new
pressure if the volume is decreased to
3
.0 L?
