Re: [計量] 五題計量問題?
※ 引述《abc03301016 (123)》之銘言：
: Q1. The arithmetic mean and standard deviation of a certain
: normal distribution are 13.5 and 1.5, respectivly.What value
: is exactly 2 standard deviations less than the mean?
: Ans:10.5
要求小於平均值兩個標準差的數
13.5 - 1.5*2
: Q2. One week a certain truck rentak lot had a total of 20
: trucks, all of which were on the lot Monday morning.
: If 50 percent of the trucks that were rented out during
: the week were returned to the lot on or before Saturday
: morning of that week, and if there were at least 12 trucks
: on the lot that Saturday morning, what is the greatest
: number of different trucks that could have been rented out
: during the week?
: Ans:16
在星期中，一半租出去的車在星期六前還回來，
星期六早上有12台，問租出去幾台？
因為星期六早上有12台，代表有8台沒有還回來，
所以總共租出去8*2台。
: Q3. Two trains, X and Y started simultaneously from opposite
: ends of a 100-mile route and traveled toward each other on
: parallel tracks. Train X travling at constant rate, completed
: the 100-mile trip in 5 hours; train Y traveling at a constant
: rate, completed the 100-mile trip in 3 hours. How many mile
: had train X traveled when it met train Y?
: Ans: 37.5
x時速20miles，y時速100/3miles，
設t時相遇，
20t + 100t/3 = 100，(x走過的路程+y走過的路程=總距離100miles)
t = 15/8
x走了 15/8*20 miles。
: Q4. A tourist purchased a total of $1500 worth of travler's checks
: in $10 and $50 denominations. During the trip the tourist cached
: 7 checks and then losts all of the rest. If the number of $10 checks
: cashed was one more or one less than the number of $50
: checks cashed, what is the minimum possible value of the checks
: that were lost?
: Ans: $1,270
總共有1500元。
花掉7張鈔票，10元的比50元的多發一章或是少花一張，
其他的都丟了，要求最小可能丟掉的錢。
那就算花最多的可能，3張10元+4張50元=230元。
其他的都丟了。
: Q5. Coins are to be put into 7 pockets so that each pocket contains at least
: one coin. At most 3 of the pockets are to contain the same number of coins
: and no two of the remaining pockets are to contain an equal number
: of coins. What is the least possible number of coins needed for the
: pockets?
: Ans: 17
7個口袋，其中3個裝一樣多的硬幣數，其他口袋的硬幣數目都不一樣，
問最少的硬幣數。
最小可能，三個一樣的放一個，其他就等比遞增，
1 1 1 2 3 4 5
共17個。
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