英语翻译Ten years ago,the mean age of a band of 11 musicians was 30.One of them is now leaving the band at the age of 40.What is the present mean age of the remaining 10 musicians?The mean of (a + 4),(b + 5),(c – 3) is 6.The mean of (a – 7),(

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英语翻译Ten years ago,the mean age of a band of 11 musicians was 30.One of them is now leaving the band at the age of 40.What is the present mean age of the remaining 10 musicians?The mean of (a + 4),(b + 5),(c – 3) is 6.The mean of (a – 7),(

英语翻译Ten years ago,the mean age of a band of 11 musicians was 30.One of them is now leaving the band at the age of 40.What is the present mean age of the remaining 10 musicians?The mean of (a + 4),(b + 5),(c – 3) is 6.The mean of (a – 7),(
英语翻译
Ten years ago,the mean age of a band of 11 musicians was 30.One of them is now leaving the band at the age of 40.What is the present mean age of the remaining 10 musicians?
The mean of (a + 4),(b + 5),(c – 3) is 6.The mean of (a – 7),(b + 13),(c – 3) is
A.5
B.6
C.7
D.8

英语翻译Ten years ago,the mean age of a band of 11 musicians was 30.One of them is now leaving the band at the age of 40.What is the present mean age of the remaining 10 musicians?The mean of (a + 4),(b + 5),(c – 3) is 6.The mean of (a – 7),(
1、十年前,一个乐队的十一名音乐家的平均年龄是30..他们中的一个现在40岁,正离开乐队.剩下的10名音乐家现在的平均年龄是什么.
解题思路:十年前他们的总年龄是30乘以11等于330.现在是十年后,那么每个人都增长了十岁,那么假设这个人还在,那么他们11个人现在的总年龄是330+10乘以11=440,这个离开的人40岁,那么剩下的人总年龄440-40=400岁,平均每个人400/10=40岁.
2、(a + 4), (b + 5), (c – 3) 的平均数是6,(a – 7), (b + 13), (c – 3) 的平均数是
A. 5
B. 6
C. 7
D. 8
解题思路:(a + 4), (b + 5), (c – 3) 的平均数是6,那么他们三个相加等于18.即a+b+c+6=18,所以a+b+c=12.要我们求的那三个式子不妨我们也把他加起来,就变成了a+b+c+3=12+3=15,
所以哪三个式子的平均数是15除以3等于5,选A选项.