A woman started a business with a workforce of 50 people. Every two weeks the number of people in the workforce increased by 3 people.
a) How many people were there in the workforce after 26 weeks?
2 weeks = 3 more people
26 weeks = 13 additions so, 13 X 3 = 39 + 50 = 89. this was correct.
b) Each member of the workforce earned $600 per week. What was the total wage will for this 26 weeks?
My working:
$600 per person per week
first 2 weeks = 2 (600 X 50) = $60 000
so a is 60 000
Every 2 weeks, which can be said to be one addition as it is constant, 2 (3 X 600) = $3600 is added
So d is 3600
n is (26/2 + 1) = 14
Sum = n/2 (2a + (n-1)d)
= 7 (120 000 + (13)3600)
= $1 167 600
This is wrong. The correct answer is $1 341 600. What am I doing wrong???