The times, in minutes after 6 a.m., that trains depart from a station during the morning are given by the set \(T = \{x : 0 \leqslant x \leqslant 90, x \tex...
Question 1 Report
The times, in minutes after 6 a.m., that trains depart from a station during the morning are given by the set \(T = \{x : 0 \leqslant x \leqslant 90, x \text{ is a multiple of } 15\}\). Work out the value of \(n(T)\), showing the members of \(T\) you have used. (3)
Answer Details
Listing every value that satisfies the set's condition, then counting them, gives \(n(T)\); here the condition restricts \(T\) to multiples of 15 within a given range.
The members of \(T\) satisfying \(0\leqslant x\leqslant90\) and "\(x\) is a multiple of 15" are \(0, 15, 30, 45, 60, 75, 90\). [1 mark]
This is every multiple of 15 from 0 up to 90 inclusive. [1 mark]
Counting them gives \(n(T) = 7\). [1 mark]
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