OCR H240/01 2022 June — Question 8

Exam BoardOCR
ModuleH240/01 (Pure Mathematics)
Year2022
SessionJune
TopicExponential Functions

8
  1. Substance \(A\) is decaying exponentially such that its mass is \(m\) grams at time \(t\) minutes. Find the missing values of \(m\) and \(t\) in the following table.
    \(t\)01050
    \(m\)1250750450
  2. Substance \(B\) is also decaying exponentially, according to the model \(m = 160 \mathrm { e } ^ { - 0.055 t }\), where \(m\) grams is its mass after \(t\) minutes.
    1. Determine the value of \(t\) for which the mass of substance \(B\) is half of its original mass.
    2. Determine the rate of decay of substance \(B\) when \(t = 15\).
  3. State whether substance \(A\) or substance \(B\) is decaying at a faster rate, giving a reason for your answer.