2025 GESS PRELIMS P2 Q7

2025 GESS PRELIMS P2 Q7

Secondary 4
7 marks

The waiting times, in minutes, for 50 patients at the Accident and Emergency clinics in two hospitals are given below.

Hospital A: Time (mins)No. of patients
\(20<t\leq24\)\(8\)
\(24<t\leq28\)\(10\)
\(28<t\leq32\)\(21\)
\(32<t\leq36\)\(7\)
\(36<t\leq40\)\(4\)

For Hospital B, the mean is 29.12 and the standard deviation is 3.2.

  1. Calculate the mean and standard deviation of the waiting times in Hospital A.
    Mean[1]
    Standard deviation[2]
  2. Compare briefly the waiting time for the A&E clinics in both hospitals.[2]
  3. Two patients are selected at random from the 50 patients in Hospital A. Find the probability of selecting one patient having to wait 24 minutes or less and the other having to wait more than 32 minutes.[2]

Solution:

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Answer:(a) Mean \(29.12\text{ min}\), SD \(4.47\text{ min}\) (b) Same mean; B is more consistent (c) \(\frac{88}{1225}\)

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