T.F. A fair die is to be rolled 90 times. If X represents the number of times a six is observed then the expected value of
X,E(X)
, is equal to:
What is 15?
T. F. A random variable X has a probability density function as shown:
the value of k is:
What is 5?
T. F. Explain what would happen to a confidence interval if you increased the sample size but the sample proportion and level of confidence stayed the same:
The width of the confidence interval would decrease.
Tech Active
Pr(Z<−1.983), where Z is a standard normal random variable is closest to
What is 0.0237?
Tech Free! The area of triangle LMN, in
cm^2 is:
What is
15 sin 40^o
Tech Free! Evaluate
What is 9?
T. F. Let X be the number of female children born into a family in a particular country, where the probability of a child being female is 0.48. An expression for the probability that a family with five children will have two female children is:
What is
5C2(0.48)^2(0.52)^3?
T. A. If a random variable X has a probability density function:
f(x)={(3/50(x^2-4x+5),0<=x<=5),(0, elsewhere):}
the mean of X is:
What is 3.125?
Tech Active
Bunnings are 95% sure that 15% to 25% of shoppers prefer to buy their christmas lights. What sample size was needed for this level of confidence?
What is 246?
Tech Active
If a random variable X is normally distributed with a mean of 100 and a standard deviation of 10, then Pr(82<X<112) is closest to:
What is 0.8490?
Tech Active
In a triangle ABC, a=5, b=6 and C= 105^@.
The length of side c is:
What is 8.75
Tech Free
For the function,
f(x)=8x^3-x^4,
the coordinates of the global maximum and the domain for which f(x) is concave up are:
Maximum at (6, 432)
Concave up for 0<=x<=4
T. A. If the proportion of batteries that are defective is 0.0030, then the standard deviation of the number of defective batteries in a sample of size 1000 is closest to (assume a binomial distribution):
What is 1.729?
T. A.
What is 0.6?
T. A. Suppose that 12% of the people in a certain country have red hair. If a random sample of 65 people is selected from that country, the mean and standard deviation of the proportion of people with red hair in the sample are:
What is
Tech Free!
The results of a state wide exam are normally distributed. If the middle 68% of entrants scored between 8 and 12 points, the approximate mean and standard deviation of the distribution are:
What is
mu=10, sigma=2.
Tech Active
The equation 2sin(2theta)=1.56 over the domain 0<=theta<=pi/2, has solution(s):
What is 0.447c or 1.123c.
Tech Free
Given that for f(x)=xsinx,
f′(x)=sinx+xcosx,
an antiderivative of xcosx is:
xsinx+cosx
T. F. Suppose the random variable X represents the number of heads recorded when a fair coin is tossed 100 times.
The mean and the variance of X are equal to:
What is E(X)=50, Var (X)=25?
T. F. X is a continuous random variable with a probability density function defined by
f(x)={(1/2x,0<=x<=2),(0, elsewhere):}
F(x), the cumulative distribution function for f(x) is:
What is
F(x)={(0, x<0),(x^2/4, 0<=x<=2),(1, x>2):}
T. A. If a researcher increases her sample size by a factor of 9, then the width of a 95% confidence interval would:
What is decrease by a factor of 3?
Tech Active
The weight of a certain breed of cat is normally distributed with a mean of 3.3 kg and a standard deviation of 1.0. If there are 50 cats of this breed at a cat show, the approximate number expected to weigh more than 4 kg:
What is 12?
Tech-Free! A block of land is in the shape of an isosceles triangle. The unequal side is 4km in length and the equal angles are labelled beta where cos(beta)=(sqrt5)/3
The exact areas of this site is:
What is
(8sqrt(5))/5 km^2
Tech Free
Solve the equation
logx(5x-6) = 2
What is x = 2 and x = 3?
T. F. A binomial distribution with n independent trials, each with probability of success p, the mean and variance are 5 and
4 1/6
respectively. The values for n and p are:
What is n=30 and p=
1/6?
T. A. A teacher has determined that the bottom 20% of students will be asked to re-sit the maths test. If the distribution of scores on the test is a random variable X with a probability density function:
then the maximum score for which a student will be asked to re-sit the examination is closest to:
What is 29.5?
T. A. A survey is conducted to determine the percentage of students in Year 12 who intend to go take a gap year after they finish secondary school. In a random sample of 200 students 18% indicated this intention. Determine a 99% confidence interval for the percentage of students in Year 12 who intend to take a gap year.
What is (0.11, 0.25)?
Tech Active
Scores on an exam are known to be normally distributed, with a standard deviation of 9.69. If 9% of the people who sat for the exam scored more than 75 marks, then the mean examination score is closest to:
What is 62?
Tech Active
A triangle has two sides of length 9.5cm and 13.5cm, and one angle of 40.2^@.
The area of two of the possible triangles are:
What are 41.39, 59.12, 61.41 and 28.41 cm2.
Tech Free
The acceleration (in m/s2) of a particle moving in a straight line is given by
(dv)/(dt)=4e^t-6t+1
where v is the velocity at any time.
If the particle starts at the origin with a velocity of -1m/s, the displacement from the origin after 1 second is:
What is
4e-19/2 metres