8 notebooks costs $16.80, 5 pens costs $15.25. Anna buys 4 notebooks and 8 pens, Benny buys 5 notebooks and 10 pens. All 2 gives the shopkeeper 2 $20 notes. Who recived more money and recived more than how much money?
Nguyễn Mạnh Hùng 16/02 at 13:23
A notebook costs: 16.80 : 8 = 2.10 ($)
A pen costs: 15.25 : 5 = 3.05 ($)
Anna buys: 2.10 x 4 + 3.05 x 8 = 8.40 + 24.40 = 32.80 ($)
Anna received: 2 x 20 - 32.80 = 7.20 ($)
Benny buys: 5 x 2.10 + 10 x 3.05 = 10.50 + 30.50 = 41 ($)
Benny received: 2 x 20 - 41 = -1 ($)
=> Anna received more and more than: 7.20 + 1 = 8.20 ($)
Linda has oranges and bunch of grapes. She wants exchange to get watermelons. 5 oranges can exchange for 1 bunch of grapes. 5 bunch of grapes can exchange for 1 watermelons. How many oranges can exchange for 3 watermelons?
Huy Toàn 8A (TL) 05/08/2018 at 13:38
Sum of odd-numbered digits ( - ) Sum of even-numbered digits or vice versa is divisible by 11
(2 + D + D) - (3 + 6 + 9) is divisible by 11
<=> 2 + 2D - 18 is divisible by 11
<=> 2D - 16 is divisible by 11
<=> 2 (D - 8) is divisible by 11
So Greatest common divisor (2 ; 11) = 1
=> D - 8 is divisible by 11
0 \(\le D\le9\)
=> D = 8
So The answer is : 386,892Selected by MathYouLike
Drew purchased a used 50-page book at the book fair. Drew later realized that the book, in which left-hand pages contained even page numbers and right-hand pages contained odd page numbers, did not contain all 50 pages. The sum of the page numbers on the pages that Drew’s book did contain was 1242. What is the greatest page number that could be on a page missing from Drew’s book?
Three identical boxes contain tennis balls, baseballs or both. A label is affixed to each box. The three labels correctly describe the three boxes, but none of the labels is on the correct box. Box 1 is labeled “Tennis Balls.” Box 2 is labeled “Baseballs.” Box 3 is labeled “Tennis Balls & Baseballs.” Devon reaches into Box 3 and pulls out a baseball. Which box contains only tennis balls?
In a survey, 30 people reported that they enjoy some combination of walking, hiking and jogging. The number who enjoy only walking, the number who enjoy only hiking and the number who enjoy only jogging are all equal. Likewise, the number who enjoy only walking and hiking, the number who enjoy only walking and jogging and the number who enjoy only hiking and jogging are equal. In addition, the survey showed that half as many people enjoy exactly two of these activities as those who enjoy only one activity. If three people enjoy all three activities, how many people enjoy jogging?
Celia, Desi and Everett are each wearing a hat that displays a different whole number from 1 to 9, inclusive. Each number cannot be seen by the person wearing it, but that number is visible to the other two individuals. Everett says, “The sum of the numbers I see is 6.” Celia says, “The product of the numbers I see is 10.” What is the sum of the numbers that Everett could possibly have on his hat?
Sam, Taylor and Pat counted the number of fish in each of their fish tanks. They noticed that Sam’s tank had exactly 25% more fish than Taylor’s tank, and Pat’s tank had exactly 24% more fish than Sam’s tank. If each tank had at least one fish, what is the minimum combined number of fish that could have been in the three tanks?
Colby is practicing his basketball shots. He knows that he has a 0.7 chance of making each 2-point shot and a 0.4 chance of making each 3-point shot. If he takes five 2-point and five 3-point shots, what is his probability of earning 20 points or more? Express your answer as a decimal to the nearest thousandth.