Numeracy Higher June 2019 Unit 1 Q8
8. Bronwen is investigating the increase in the growth of algae on the surface of a pond.
The surface area covered by the algae is measured in cm2.
She finds the surface area covered by the algae \(t\) days after the start of her investigation is given by the following expression.
(a) What surface area was covered by algae at the start of her investigation?
Circle your answer. [1]
Circle your answer. [1]
404 cm2 401 cm2 4 cm2 402 cm2 400 cm2
(b) Bronwen calculated the surface area covered by the algae 5 days after the start of the investigation.
She also calculated the surface area 7 days after the start of the investigation.
By how much did the surface area covered by the algae increase between these two times? [3]
She also calculated the surface area 7 days after the start of the investigation.
By how much did the surface area covered by the algae increase between these two times? [3]
| Scheme | Marks | Comments |
|---|---|---|
| 401 (cm2) | B1 |
| Scheme | Marks | Comments |
|---|---|---|
| A correct evaluation of (47/2 =) 128 OR (45/2 =) 32 | B1 | or sight of appropriate 528 OR 432 |
| (400 + 47/2) – (400 + 45/2) OR 47/2 – 45/2 or equivalent | M1 | (528 – 432 OR 128 – 32) |
| = 96 (cm2) | A1 | CAO |