This problem comes from the Scottish Mathematical Council (SMC) Senior Mathematical Challenge of 2008:
“S2. In Tiffany’s, a world famous jewellery store, there is a string necklace of 33 pearls. The middle one is the largest and most valuable. The pearls are arranged so that starting from one end, each pearl is worth $100 more than the preceding one, up to [and including] the middle one; and starting from the other end, each pearl is worth $150 more than the preceding one, up to [and including] the middle one. If the total value of the necklace is $65,000 what is the value of the largest pearl?”
I included the words in brackets to erase any ambiguity.
See the Pearl Necklace Problem