Question 4. Some students are nervous about their first Statistics class. To test whether taking her class might decrease students' anxiety about the subject, a professor surveyed students anxiety about Statistics at the beginning and end of her course. Anxiety levels were measured on a scale of 0 (not anxious at all) to 10 (extremely anxious). Here are the data for 16 randomly chosen students from a class of 180 students. For a single student, each column shows a score before the course, after the course, and the difference between the two. Row Row Mean SD Before 4.81 2.23 7 6 9 5 6 7 5 7 4 3 2 1 3 4 2 course After 3.69 1.54 4 3 7 4 5 4 5 3 3 1 4 course Difference (Before -3 -3 -2 -2 -2 -2 -1 -1 -1 -1 0 0 1 -1.06 1.18 - After) Do the data indicate that anxiety levels about the field of Statistics decreased over the course of the semester? Test an appropriate hypothesis and state your conclusion. 3. 3. 3.

17) Identify the cumulative frequency distribution that corresponds to the given frequency distribution. 17) Number Speed of Cars 0-29 4 30-59 16 60-89 60 90-119 20 A) B) Cumulative Speed Frequency 0-29 4 30-59 60-89 80 90-119 100 Cumulative Speed Frequency Less than 30 0.04 Less than 60 0.20 Less than 90 0.80 Less than 120 1.00 20 D) Cumulative Speed Frequency Less than 30 1 Less than 60 20 Less than 90 80 Less than 120 Cumulative Speed Frequency Less than 30 100 Less than 60 80 Less than 90 82 Less than 120 4 100 18) 18) Find the standard deviation for the given sample data, Round your answer to one more decimal place than the original data. 22.6 16.1 36.1 36.0 23.8 20.3 A) 3999.0 B) 8.35 C) 4347.7 D) 36.1

Help please A thin walled cylindrical pressure vessel is subjected to an internal pressure which varies from 750 KPa to 3550 KPa continuously. The diameter of the shell is 1.5 m. Find the required thickness of the cylinder wall based on yield point of 480 MPa, net endurance limit of 205 MPa and a factor of safety of 2.5. A camshaft 19 mm. in diameter is mounted on ball bearings and carries a cam midway from the bearings. The follower, which weighs 2.8 KN, is out of adjustment so that impact is produced when it is contacted by the cam. The height h of fall equals 0.254 mm. The shaft is made of AISI C1045 steel. Determine the maximum bending stress in the shaft.

Consider the following diagram: Internet Modem Wireless AP Switch Wireless AP DO Wireless AP Server 2.1 Using a table, compare 4 types of area networks. Consider the size of the network and the transmission media that is most likely to be found in each type of network. (8) 2.2 Based on the information given in 2.1, which type if network is shown in the Consider the following diagram: Internet Modem Wireless AP Switch Wireless AP DO Wireless AP Server 2.1 Using a table, compare 4 types of area networks. Consider the size of the network and the transmission media that is most likely to be found in each type of network. (8) 2.2 Based on the information given in 2.1, which type if network is shown in the diagram? Motivate your (2) answer. 2.3 This network has wireless access points. Compare three modulation techniques, using sketches, that could be used by these access points to transmit data. Use the bit-stream 10000101111. (6)

Biostatistics ESSAY A firm investigates the length of telephone conversations of their office staff. Ten consecutive conversations had lengths, in minutes: 10.7, 9.5, 11.1, 7.8, 11.9, 4.1, 10.0, 9.2, 6.5, 9.2. Derive a 95% confidence interval for the mean conversation length. Test whether the mean length of a conversation is eight minutes.(25 MARKS)

P3.5 The sales revenue, food cost of sales, and guests served for a small fast- food carryout division of a restaurant for the past six months are given below. Sales Month Cost of Revenue Guests Served Sales, Food 1 2. 4 $258,200 274,800 285,600 289,400 298,300 304,600 $ 96,200 104,300 110,500 113,100 118,900 123,700 10,200 10,400 10,300 10,100 10,400 10,500 6 For each of the six months calculate average check and average costs of sales food. Using these averages, calculate an index number. Set the in- dex for month 1 at 100 and complete index numbers for the remaining five months. With the index numbers identified, convert sales revenue and cost of sales food from historic to current dollars.

A cylindrical rock sample has a length of 6 cm, a diameter of 4 cm, and a dry weight of 166.4 g. When fully saturated with an oil of density 0.85 g/cm3, the weight of this sample is 176.9 g. Assuming constant temperature, find: i) The porosity of the sample ii) The pore compressibility of the sample, given that 0.2 cm of oil leaves the sample when a pressure of 3200 psig is applied on it iii) The amount of oil that can be extracted from the sample when a pressure of 2000 psig is applied on it