Refer to the data set tunnel.csv. Find a confidence interval of the specified level for the mean speed in each of the following types of soil.

a. GSG soil, $95\%$ confidence

b. CCS soil, $98\%$ confidence

c. GSF soil, $99\%$ confidence

d. GSGu soil, $90\%$ confidence

Tunnel Data Set:
A tunnel boring machine, used to construct underground tunnels, contains a large circular cutting wheel which rotates as the machine drives forward, breaking material which is moved to the rear of the machine via a conveyor belt. The speed with which the machine moves forward is known as the advance rate. Both the advance rate and the cutting wheel torque are influenced by the type of soil the machine is moving through.
There are four soil types in this data set: granular sand and gravel (GSG), cohesive clay and silt (CCS), granular silt and fine sand (GSF), and unsaturated granular sand and gravel (GSGu). Granular soils are those that are free running, such as sand, while cohesive soils are those that tend to hold together, such as clay. Unsaturated soils are those where water pressure is less than atmospheric pressure, so water does not flow out of the soil. Following is a list of the variables in this data set:

Transcribed Image Text:

Torque Cutting wheel torque (in MN-m) Advance rate (in mm/min) Speed Soil Type of soil (GSG, CCS, GSF, or GSGu)