Question

Mr Sun knitted 6 scarves in 16 hours. She took 40 minutes longer to knit the second scarf than the first one, 40 minutes linger to knit the third scarf that the second one as so on. How long(in minutes) did she take to knit the first scarf?

Answer 1

Hey bro!!

Here is your answer!
Final result: 60 minutes.

According to the question, we get

an AP of common difference,
d = 40 min

No. of terms ,n = 6 scarves
First term , a = ?
Sum of first 6 terms = 16*60=960 min

We know that ,
$s(n) = \frac{n}{2} (2a + (n - 1)d)$
$s(6) = \frac{6}{2} (2a + (6 - 1)40) \\ 960 = 3(2a + 5 \times 40) \\ 320 = 2a + 200 \\ a = 60$
Therefore,
Mr Sun takes 60minutes to knit the first scarf.

Hope, you understand my answer and it may helps you.