Update, 8 p.m., Sept. 25, 2018: The contest is now closed and no more guesses will be accepted or posted. We will announce the correct answer tomorrow and will also randomly choose a winner, who will be notified directly by email. Thanks to everyone who participated. And if you missed this question, we’ll be doing another one at the end of October. Keep an eye on our social media channels for announcements.

Ready to take your shot at winning a $50 Amazon gift card? You’ll have a chance if you correctly answer today’s energy efficiency trivia question. It’s the fourth of five of questions we’re posting this summer and fall.

The full official rules are here, but here’s the short version:

•Each question will be posted here on our Stories blog at 8 a.m. on contest day. (We’ll promote them on social media beforehand — particularly on Twitter and Facebook — so be sure you’re following us.)

• You’ll have until 8 p.m. that same day to post your answer in the Comments section of the blog post. Answers posted on any other social media platform, or posted after 8 p.m. on contest day, will not be eligible to win.

•One correct response will be chosen at random, and the winner will receive a $50 Amazon gift card. Make sure to leave a valid email address as part of your comment, so we can reach you if you win — if we can’t reach you, we’ll have to choose another winner.

Also, we reserve the right to hide or delete comments not related to the contest. If you need help with a customer service issue, the best way to handle it is to call us at 1-800-DIAL-PPL (that’s 800-342-5775.)

Now that that’s out of the way, here’s this month’s energy efficiency trivia question. Remember, answers go in the comments:

According to the U.S. Department of Energy, sealing uncontrolled air leaks can save you how much on your annual energy costs, by percent?