An online store receives customer satisfaction ratings between 0 – 100, inclusive. In the first 10 ratings the store received, the average (arithmetic mean) of the ratings was 75. What is the least value the store can receive for the 11th rating and still be able to have an average of at least 85 for the first 20 ratings.题目主要意思为：一家在线商店会收到评分为0-100分之间的顾客满意度评价，收到的前10个评价得分平均为75，如果要保证前20个评价的平均得分为85，商店收到的第11个评价的最少为多少分?大家可以发现题目非常贴近我们的生活，在网购如此发达的中国，相信大家作为买家都给过店家评价吧。在这道题中，商店需要计算好评率。这类题我们都可以看做“应用题”，解答应用题首先需要将题目给出的情境抽象化：在0-100中先按顺序选择10个数，他们的平均数为75，如果再依次选择10个数，为了保证这20个数的平均数为85，第11个数最少应该是几?
A bank has opend a new branch and ,as part of a promotion, the bank branch is offering $1,000 certificates of deposit at an interst rate of 4% per year, compounded semiannually. The bank is selling certificates with terms of 1,2,3 or 4 years. Which of the following fuctions gives the total amount, A, in dollars, a customer will receive when a certificate with a term of k years is finnally paid.
The cost of using a telephone in a hotel meeting room is $0.20 per minute. Which of the following equations represents the total cost c, in dollars, for h hours of phone use?
Michael swam 2,000 yards on each of eighteen days. The scatterplot above shows his swim time for and corresponding heart rate after each swim. The line of best fit for the data is also shown. For the swim that took 34 minutes, Michael’s actual heart rate was about how many beats per minutes less than the rate predicted by the line of best fit?
要求：具备相应的科学背景知识、信息处理能力以及逻辑推理能力The speed of a sound wave in air depends on the air temperature. The formula above shows the relationship between a, the speed of a sound wave, in feet per second, and t, the air temperature, in degrees Fahrenheit (°F). Which of the following expresses the air temperature in terms of the speed of a sound wave?
The number of states that joined the United States between 1776 and 1849 is twice the number of states that joined between 1850 and 1900. If 30 states joined the United States between 1776 and 1849 and x states joined between 1850 and 1900, which of the following equations is true?
In order to determine if treatment X is successful in improving eyesight, a research study was conducted. From a large population of people with poor eyesight, 300 participants were selected at random. Half of the participants were randomly assigned to receive treatment X, and the other half did not receive treatment X. The resulting data showed that participants who received treatment X had significantly improved eyesight as compared to those who did not receive treatment X. Based on the design and results of the study, which of the following is an appropriate conclusion?A) Treatment X is likely to improve the eyesight of people who have poor eyesight.B) Treatment X improves eyesight better than all other available treatments.C) Treatment X will improve the eyesight of anyone who takes it.D) Treatment X will cause a substantial improvement in eyesight.解读：这道题给我们简述了一个改善视力科学实验，从实验对象的选择，分组到进行实验，最后要求学生根据以上信息得出科学结论。