问答题What is the average (arithmetic mean) of x and y? (1) The average of x+3 and y+5 is 14. (2) The average of x,y and 16 is 12.
题目
问答题
What is the average (arithmetic mean) of x and y? (1) The average of x+3 and y+5 is 14. (2) The average of x,y and 16 is 12.
相似考题
参考答案和解析
正确答案：
D
解析：
将两条件分别代入计算可知，x和y的平均数均为10，故本题选D项。
将两条件分别代入计算可知，x和y的平均数均为10，故本题选D项。
更多“问答题What is the average (arithmetic mean) of x and y? (1) The average of x+3 and y+5 is 14. (2) The average of x,y and 16 is 12.”相关问题
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第1题：
问答题What is the value of x-y? (1) (x-y)2=25 (2) 4x=4 (y+3)正确答案： B解析：
条件1不能确定x-y的值，由条件2可知，x-y=3，故本题选B项。 -
第2题：
单选题If the average of x and y is 11/2 and the average of 1/x and 1/y is 11/24, then xy =______.A4
B6
C11
D12
E14
正确答案： C解析：
Since the average of x and y is 11/2, then, (x + y)/2 = 11/2 or x + y = 11. If the average of 1/x and 1/y is 11/24, then (1/2)(1/x + 1/y) = 11/24 or 1/x + 1/y = 11/12. Since 1/x + 1/y = (x + y)/xy and x + y = 11 then 11/xy = 11/12, so xy=12. -
第3题：
单选题What is the average (arithmetic mean) of 8 consecutive odd integers if the smallest of those integers is n?An+5
Bn+6
Cn+7
Dn+8
En+9
正确答案： D解析：
最小的整数为n。它们是连续的奇数。这组整数为:n,n+ 2, n+4, n+6, n+8, n+10, n+12, n+14。计算这些整数的平均数即为将它们想加除于8。得出（8n+56）/8=n+7 -
第4题：
问答题An aircraft flew from A to B at an average speed of 230 mph. It returned from B to A at an average speed of 300 mph. What was its average speed for the two journeys?正确答案： 260 mpf解析：
设飞机从A到B耗时a小时，从B到A耗时b小时，那么可得出230a=300b；飞机飞行整个路程中所用的平均速度则为300b/(a+b)；将两个方程式合并，便可得出平均速度约为260.3 mpf，四舍五入后取结果260mpf。 -
第5题：
问答题If x+y=36, what is the value of xy? (1) y-x=14 (2) y=2x+3正确答案： D解析：
分别将两个条件代入题目，可以计算出x=11，y=25，故本题应选D项。 -
第6题：
问答题At the eating contest the winner ate an average of 15 hot dogs at the first 20 sittings. After a further 20 sittings the average increased to 20 hot dogs. What was the average for the last 20 sittings?正确答案： 25.解析：
前20轮共吃汉堡300个，40轮下来共吃汉堡800个，则后20轮吃汉堡500个，因此每轮吃25个。 -
第7题：
单选题在速度为v＝2m/s的水平直线流中，在y轴下方5个单位处放一强度为3的汇流，则此流动的流函数为（ ）。[2012年真题]Aψ＝2y－[3/（2π）]arctan[（y＋5）/x]
Bψ＝2y＋[3/（2π）]arctan[（y＋5）/x]
Cψ＝2x－[3/（2π）]arctan[（y－5）/x]
Dψ＝2x＋[3/（2π）]arctan[（y－5）/x]
正确答案： B解析：
此流场为均匀直线流与汇流的叠加，即ψ＝ψ1＋ψ2。在均匀直线流动中，流速为常数，ux＝v＝2m/s，uy＝0，则ψ1＝uxy－uyx＝2y；当流体从四方向某汇合点集中，这种流动称为汇流，汇流的流体方向与源流相反，汇点在（0，－5），强度为3的流函数为ψ2＝－[Q/（2π）]θ＝－[3/（2π）]arctan[（y＋5）/x]。叠加后为：ψ＝ψ1＋ψ2＝2y－[3/（2π）]arctan[（y＋5）/x]。 -
第8题：
问答题If a is an integer, is b an integer? (1) The average (arithmetic mean) of a and b is an integer. (2) The average (arithmetic mean) of a, b, and b+4 is a.正确答案： D解析：
根据算数平均数的定义可知，本题应选D项。 -
第9题：
单选题The average (arithmetic mean) of five numbers is 10. The sum of three of the numbers is 30. What is the sum of the other two numbers?A5
B10
C20
D30
E40
正确答案： C解析：
The arithmetic mean of the five numbers is 10. That means the sum of the numbers is 50. The sum of three numbers is 30. so the sum of the remaining two numbers is 50-30 = 20. -
第10题：
单选题For integer values of the age from 10 months to 14 months, the average (arithmetic mean) weight falls approximately between ______ pounds.A750 and 850
B850 and 950
C950 and 1050
正确答案： C解析：
在10个月时，大象的体重大约为800磅，到了14个月大象的体重大约为1000磅，在这期间大象的体重变化比较平稳，因此体重平均数大约为900磅，故答案选B。 -
第11题：
单选题The average (arithmetic mean) of x and y is m, where m ≠ 0. What is the average (arithmetic mean) of x, y, and 2m?Am
B4/3m
C3/2m
D5/3m
E2m
正确答案： D解析：
因为x和y的算术平均数为m，所以x+y=2m，所以，所以x,y,2m的算术平均数为x+y+2m/3，因为x + y = 2m，所以x+y+2m/3=4m/3 -
第12题：
问答题MegaTech and UltraCorp are considering a merger to form the MegaUltraTech Corporation. Does MegaTech have more employees than UltraCorp? (1) The average (arithmetic mean) age of UltraCorp employees is 32.8, while the average age of MegaTech employees is 27.2. (2) If the merger goes through and all employees from both companies remain employed, the average (arithmetic mean) age of the MegaUltraTech employees will be 31.4.正确答案： C解析：
条件1、2中均不涉及两个公司的员工数量，但是将两者综合可以推断出UltraCorp的员工数大于MegaTech，故本题选C项。 -
第13题：
单选题If the average of 8 and x is 10 and the average of 7 and y is 11, what is the average of x and y?A9.0
B10.5
C12.0
D13.5
E15.00
正确答案： C解析：
因为8和x的平均数为10，可得出(8+x)/2=10，x=12。又因为7和y的平均数为11，所以可得出7 + y = 22，y=15，所以x和y的平均值为(x+y)/2=(12+15)/2= 27/2=13.5。 -
第14题：
单选题The average (arithmetic mean) of c and d is 12, and the average of c, d, and e is 10. What is the value of e?A6
B10
C12
D18
E20
正确答案： A解析：
根据题目中已知的数量关系，可列等式如下：c+d= 12×2=24……①；c+d+e=10×3=30……②。把等式①代入等式②得，24+e=30，e=6。 -
第15题：
问答题If 10a + 10b =35, what is the average (arithmetic mean) of a and b?正确答案： 1.75解析：
由10a+10b=35可得10(a+b)=35→a+b=3.5，所以a和b的平均数是3.5÷2=1.75。 -
第16题：
问答题At the beer-drinking contest the winner drank an average of 10 bottles of beer at the first 20 rounds. After a further 20 rounds the average increased to 15 bottles. What is the average for the last 20 rounds?正确答案： 20.解析：
在前20轮中胜者平均喝10瓶酒，共喝200瓶。再过20轮后平均喝15瓶，即共喝了40×15=600瓶。故，后20轮喝了400瓶，胜者平均喝20瓶。 -
第17题：
单选题If x-9 = 2y and x+3 = 5y, what is the value of x?A-2
B4
C11
D15
E17
正确答案： A解析：
Subtract corresponding sides of the two given equations: x+3=5y, x- 9= 2y →0+ 12=3y. 12/3 = y or y=4. Since y= 4 and x + 3 = 5y, then x + 3 = 5(4) = 20, so x=20-3=17. -
第18题：
单选题1. public class X implements Runnable（ 2. private int x； 3. private int y； 4. 5. public static void main（String[]args） 6. X that = new X（）； 7. （new Thread（that））.start（）； 8. （new Thread（that））.start（）； 9. ） 10. 11. public void run（） （ 12. for （；；） （ 13. x++； 14. y++； 15. System.out.printIn（“x=” + x + “， y = ” + y）； 16. ） 17. ） What is the result？（）AErrors at lines 7 and 8 cause compilation to fail.
BThe program prints pairs of values for x and y that might not always be the same on the same line （for example， “x=2， y=1”）.
CThe program prints pairs of values for x and y that are always the same on the same line （for example， “x=1， y=1”. In addition， each value appears twice （for example， “x=1， y=1” followed by “x=1， y=1”）.
DThe program prints pairs of values for x and y that are always the same on the same line （for example， “x=1， y=1”. In addition， each value appears only for once （for example， “x=1， y=1” followed by “x=2， y=2”）.
正确答案： C解析： 暂无解析 -
第19题：
单选题If 70% of the bananas in a particular harvest had an average (arithmetic mean) length of 7 inches and 30% of the bananas in that harvest had an average (arithmetic mean) length of 5 inches, what was the average (arithmetic mean) length, in inches, of all of the bananas in the harvest?A6.0
B6.2
C6.4
D6.6
E6.8
正确答案： B解析：
假设共有100个香蕉，根据题干全部香蕉的长度为(100×70%×7)+(100×30%×5)=640英尺，共有100只香蕉，所以平均每只香蕉的长度为640/100=6.4。故选C。 -
第20题：
问答题If M is a set of five numbers p, q, r, s and t, is the range of numbers in M greater than 5? (1) The average (arithmetic mean) of p, q, r, S, and t is 5. (2) p-r>5.正确答案： B解析：
条件1不能判断M数集的极差；由p-r>5可知p、r间的距离大于5，故M的极差大于5，所以本题应选B项。 -
第21题：
单选题The average (arithmetic mean) of a set of seven numbers is 81. If one of the numbers is discarded, the average of the remaining numbers is 78. What is the value of the number that was discarded?A98
B99
C100
D101
E102
正确答案： B解析：
If the average (arithmetic mean) of a set of seven numbers is 81, then the sum of these seven numbers is 7 x 81 or 567. Since, if one of the numbers is discarded, the average of the six remaining numbers is 78, the sum of these six numbers is 6×78 or 468. Since 567 - 468 = 99, the value of the number that was discarded is 99. -
第22题：
单选题If the average (arithmetic mean) of 3, 7, 10, and x is 7, then what is the median of 3,7,10, and x?A5.5
B6
C6.5
D7
E7.5
正确答案： D解析：
因为3,7,10,和x 的平均数是7，可得出等式(3+7+10+x)/4=7，(20 + x)/4= 7，20+ x = 28，x = 8。所以3,7,10,和x四个数排序为3,7,8,10，它们的中位数为(7+8)/2=7.5。 -
第23题：
单选题If the average (arithmetic mean) of a, b, 4, and 10 is 8, what is the value of a + b?A4
B6
C9
D15
E18
正确答案： B解析：
根据题干可得出(a+ b + 10 + 4)/4=8，a + b=18。