题库搜索>问题求解PS-12759
A certain list consists of 21 different numbers. If n is in the list and n is 4 times the average (arithmetic mean) of the other 20 numbers in the list, then n is what fraction of the sum of the 21 numbers in the list?
分析A选项
分析B选项
分析C选项
分析D选项
分析E选项
当前版本由 借我借我一双慧眼吧 更新于2015-12-10 11:19:02 感谢由 借我借我一双慧眼吧 对此题目的解答所做出的贡献。题目说有21个不同的数字,n是其中之一,n是剩下20个数字平均值的四倍,n是总共21个数的多少?
设平均值为k 则剩下20个数字的平均值为20k
n是平均值的四倍 n=4k
则 4k/20k+4k=1/6
N是其他20个数平均数的4倍;
所以这里可以求出n:设平均数为a:n=4a
所以21个数的中和就应该是:20a+4a=24a
所以:4a/24a=1/6
296823cl
假設20個數平均為1 n是平均值的4倍 n=4,n的佔比就會為4/(20+4)=1/6
科目:
问题求解PS
来源:
GWD
7m39s
平均耗时
85.1%
平均正确率
该题由网友WcRJtfV提供
点击上传问题求解PS -17755
Each of the integers from 0 to 9, inclusive, is written on a separate slip of blank paper and the ten slips are dropped into a hat. If the slips are then drawn one at a time without replacement, how many must be drawn to ensure that the numbers on two of the slips drawn will have a sum of 10?
问题求解PS -17752
Which of the following describes the set of all possible values of the positive integer k such that, for each positve odd integer n, the value of nk is midway between consecutive integers?
问题求解PS -17741
The sum of the first 100 positive integers is 5,050. What is the sum of the first 200 positive integers?
问题求解PS -16762
【OG20-P150-27题】Set X consists of eight consecutive integers. Set Y consists of all the integers that result from adding 4 to each of the integers in set X and all the integers that result from subtracting 4 from each of the integers in set X. How many more integers are there in set Y tha...
问题求解PS -15114
The sum of the first n positive perfect squares, where n is a positive integer, is given by the formula n33 +cn2 +n6 , where c is a constant. What is the sum of the first 15 positive perfect squares?
问题求解PS -17755
Each of the integers from 0 to 9, inclusive, is written on a separate slip of blank paper and the ten slips are dropped into a hat. If the slips are then drawn one at a time without replacement, how many must be drawn to ensure that the numbers on two of the slips drawn will have a sum of 10?
问题求解PS -17752
Which of the following describes the set of all possible values of the positive integer k such that, for each positve odd integer n, the value of nk is midway between consecutive integers?
问题求解PS -17741
The sum of the first 100 positive integers is 5,050. What is the sum of the first 200 positive integers?
问题求解PS -16762
【OG20-P150-27题】Set X consists of eight consecutive integers. Set Y consists of all the integers that result from adding 4 to each of the integers in set X and all the integers that result from subtracting 4 from each of the integers in set X. How many more integers are there in set Y tha...
问题求解PS -15114
The sum of the first n positive perfect squares, where n is a positive integer, is given by the formula n33 +cn2 +n6 , where c is a constant. What is the sum of the first 15 positive perfect squares?