Answer: it would take Tom 1 hour to make 4 keychains, 1.25 hours to make 5 keychains, 1.5 hours to make 6 keychains, and 1.75 hours to make 7 keychains.
Step-by-step explanation: To calculate the time it would take Tom to make 4, 5, 6, and 7 keychains, we need to determine the constant of proportionality between the number of keychains and the time it takes to make them.
Given that when Tom makes 6 keychains, it takes him 1.5 hours, we can calculate the constant of proportionality using the formula:
Constant of proportionality = Time / Number of keychains
Using the given values, we have:
Constant of proportionality = 1.5 hours / 6 keychains
Constant of proportionality = 0.25 hours/keychain
Now, we can use this constant of proportionality to calculate the time it would take Tom to make 4, 5, 6, and 7 keychains:
For 4 keychains:
Time = Constant of proportionality * Number of keychains
Time = 0.25 hours/keychain * 4 keychains
Time = 1 hour
For 5 keychains:
Time = Constant of proportionality * Number of keychains
Time = 0.25 hours/keychain * 5 keychains
Time = 1.25 hours
For 6 keychains:
Time = Constant of proportionality * Number of keychains
Time = 0.25 hours/keychain * 6 keychains
Time = 1.5 hours (as given in the question)
For 7 keychains:
Time = Constant of proportionality * Number of keychains
Time = 0.25 hours/keychain * 7 keychains
Time = 1.75 hours