answer:We know that in 21 hours, the heating plant consumes 7 liters of fuel. So, in 1 hour, the heating plant consumes 7/21 = 1/3 liters of fuel. Therefore, in 90 hours, the heating plant will consume 1/3 * 90 = 30 liters of fuel. 30 The answer is: 30

answer:The probability of rolling at least one 1 is equal to 1 minus the probability of rolling no 1's. The probability of rolling no 1's on one die is frac{5}{6}, so the probability of rolling no 1's on both dice is left(frac{5}{6}right)^2 = frac{25}{36}. Therefore, the probability of rolling at least one 1 is 1 - frac{25}{36} = boxed{frac{11}{36}}. The answer is: frac{11}{36}

answer:Allison's cube has a 5 on all faces, so the probability that she rolls a 5 is 1. Brian's cube has faces numbered 1-6, so the probability that he rolls a number less than 5 is frac{4}{6}=frac{2}{3}. Noah's cube has three faces with a 2 and three faces with a 6, so the probability that he rolls a number less than 5 is frac{3}{6}=frac{1}{2}. The probability that Allison's roll is greater than both Brian's and Noah's rolls is the product of these probabilities: 1 cdot frac{2}{3} cdot frac{1}{2} = boxed{frac{1}{3}}. The answer is: frac{1}{3}

answer:John purchases a heating pad for 30 and uses it three times a week for two weeks. The total number of times John uses the heating pad is 3 times/week x 2 weeks = 6 times. The cost of each use of the heating pad is 30/6 = 5. 5 The answer is: 5