Chris decided he would reward himself with 6 Darkside Skittles for each of the first nine consecutive days he completed the Question of the Day(QOTD). On the tenth day, and on all other days afterward that he continued his QOTD streak, he planned to reward himself with 7 Darkside Skittles. If d is the number of consecutive days that Chris maintained his QOTD streak, with $d$ ≥ 9, which of the following functions gives the total $s(d)$ number of Darkside Skittles that Chris rewarded himself?
The correct answer is (A).
current priority level - the Path to 650+ and higher
First, if you have never tried Darkside Skittles or did not even know they exist….
Ok, on to business. If it at some point in your test training, a word problem like this screams SUB NUMBERS to you, very good things are afoot.
Before we walk through a SN-route toward smashing this question, let’s acknowledge that test writers expect many, many, many testers to select an option like (C) here. Call such an option bait, call it a crafted wrong answer. Whatever you call this type of compelling wrong answer, be aware of its existence.
Ok, let’s say that ‘d’ is 15. We know that for the “first nine” days, Chris is rewarding himself with 6 DS a day. On the remaining 6(15 - 9) days, he is rewarding himself with 7 DS a day. We could write things out as….
9 x 6 = 54
6 x 7 = 42
…to make it crystal clear to ourselves that the total number of DS would be 96. Using $d$ as 15, the correct answer will match this 96.
When option (A) matches, it would be legitimate to stop. The likelihood that another option will match is effectively zero. Why the equation within option (A) looks the way it does, we likely want to choose to not care about. This is a known type of question within this test. SN is a known way to smash this question. An option like (C) becomes a known wrong answer that we know not to select. We know a lot.