Algebra 2
4 marks · NormalThe time (in seconds) for a task is inversely proportional to the number of people working.
If 3 people can do the task in 20 seconds, write a formula for in terms of .
How long does the task take with 5 people?
How many people are needed to complete the task in 12 seconds?
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) t = 60 / n
(b) 12 seconds
(c) 5 people
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Sets up correct proportionality: , substitutes values to find k.
A1 (a) · 1 mark · States formula: or equivalent. (follow-through)
B1 (b) · 1 mark · Correctly calculates seconds for 5 people. (follow-through)
B2 (c) · 1 mark · Correctly finds n = 5 for 12 seconds. (follow-through)
Worked solution
a) .
When .
b) seconds.
c) people.