# Oxford PAT 2011, Questions 5 and 6

N.B. There is a mistake in the answer to question 6.  The sum of the arithmetic sequence is missing a division by 2.  See the comments below for details.

## 4 thoughts on “Oxford PAT 2011, Questions 5 and 6”

1. salma wafa says:

how is 2 to the power (x-1) equal to 5?

1. We have been told that 2^x is 10. From our knowledge of indices, we know that 2^(x-1) equals 2^x divided by 2, therefore 2^(x-1) equals 5.

2. Again, thanks for the excellent site. I think, however, the answer to this one is slightly off because the sum of an arithmetic series is divided by 2 and you haven’t done that:) It should be 126 + 14 to give an answer of 140. If I’m wrong please let me know! Thanks again.

1. Yes of course you are absolutely right: I left out the division by 2. The sum of the arithmetic sequence is 6/2(2/3+12/3), which equals 14. So the total is 126 + 14, which equals 140.

Thanks very much for pointing this out: it is really useful for me and for all the other readers too. If you find any other slips, or anything you think needs clarification, then please add comments for those questions as well.