Self-study
Support John works five days each week except when on vacation or during weeks in which national holidays occur. ████ ████ █ ████ ██ █████ ██ ██ █████████ ████████ ██ ███████ ██ █████ ██ █ ███████████ ████ ████ █████ ████ ██ █████████ ███ ████ ███ ███ ██ █████████ ██████████ ██ ████ ████ ██████ ██ ███ █████████ ███████ ██ ███████ ████████ ██████████ ███ ████████ ████ █████
Summary
The author concludes that John must have worked in an insurance company from Monday through Thursday last week. This is because John always works five days per week: four days in the insurance company, and on Fridays as a blacksmith. The only exceptions are when John is on vacation or there's a holiday, and neither of these things happened last week.
Objective: Find a Necessary Assumption
The author establishes that John works in the insurance company four days per week, but never specifies which days of the week. We know John's blacksmithing on Friday, but that alone isn't enough to limit John's insurance days to Monday through Thursday. If John happened to work on the weekend, then the conclusion would not follow.
So in order to get to the conclusion, the author has to assume that John didn't work on the weekend. The argument depends on this assumption, because otherwise there's no way to limit John's days in the insurance company to Monday through Thursday. That said, just because we've spotted one necessary assumption, doesn't mean it's the only possibility. So we can look for this assumption in the answer choices, but still be aware there could be an unexpected twist.
11.
Which one of the following ██ ██ ██████████ ██ █████ ███ ████████ ████████
a
John never takes █ ████████ ██ ████ ████ ███ ████ ██ ███████
We already know that John didn't take any vacation time last week, and that's the only span of time that we care about for this argument. John's vacation habits outside of this week aren't necessary either way.
b
Every day last ████ ████ ████ ███████ ██ ██████ ███ ██ ██████ ████████
This isn't necessary because the conclusion is simply that John worked in the insurance company on those days; it doesn’t matter how long the workday was.
c
John does not ████ █████████ ██ █████ ██ █████ ████████ ████████ ██████
Like (A), it's not necessary to assume anything about John's vacation habits, because the support establishes that he had neither holidays nor vacation days last week. And that's the only week we care about!
d
Last week John ██████ ███████ ██ ████████ ███ ██ ███████
This is required for the conclusion to follow, which we can see by using negation. If (D) weren’t true, then John could have worked in the insurance company on the weekend instead of every day between Monday and Thursday. The only way the conclusion follows is if we assume (D) is true.
e
There were no ████ ████ ████ ██ █████ ████ ████ ██████ ██ ███ █████████ ███████ ███ ████ ██████ ██ █ ███████████
The conclusion is simply that John worked in the insurance company from Monday through Thursday. This could still be true if he also worked as a blacksmith on any of those days—nothing tells us John only worked in insurance those days.
If (E) were phrased differently, and specifically said that John didn't also work in the insurance company on Friday, then it might be necessary. After all, a Friday working in insurance would take away from one of the Monday through Thursday days. But as written, (E) is too broad, making it unnecessary—John could have pulled double duty on any non-Friday weekday without harming the argument.