Please help! Find the error & explain why it is wrong:
Jon wanted to solve this problem:

The number of visitors to a website in the first week is 40. The number of visitors each week is double the number of visitors the previous week. What is the total number of visitors to the website in the first 10 weeks?

What did he do wrong?

In each of the cases that follow, the magnitude of a vector is given along with the counterclockwise angle it makes with the +x axis. use trigonometry to find the x and y components of the vector. also, sketch each vector approximately to scale to see if your calculated answers seem reasonable. (a) 50.0 n at 60.0°, (b) 75 m/ s at 5π/ 6 rad, (c) 254 lb at 325°, (d) 69 km at 1.1π rad.