The average of a, b, c, d, and e is 28. If the average of a, c, and e is 24, what is the average of b and d?
A
31
B
32
C
33
D
34
E
36
正确答案:
C
解析: If the average of a, b, c, d, and e is 28, then (a + b + c + d + e)/5 = 28, or a + b + c + d + e=5×28= 140. If the average of a, c, and e is 24, then (a + c + e)/3 = 24. Or a + c + e= 3 × 24 = 72. Substituting 72 for a+c+e in a+b+c+d+e=140 gives b+d+72 = 140, b +d = 140-72 = 68, (b + D./2 = 68/2 = 34.
第5题:
日内瓦印记共多少条法则?()
A、6
B、10
C、12
D、20
正确答案:C
第6题:
基础脉搏比平时增加()次/分,提示机能不良。
A、6
B、10
C、12
D、20
正确答案:C
第7题:
四环素的有效血浓度维持约多少小时?()
A、4~6
B、8~10
C、12~14
D、16~18
E、20~22
正确答案:B
第8题:
法国波尔多所产的上佳年份的红酒,需陈酿()年以上才能成熟。
A、6
B、10
C、12
D、20
正确答案:B
第9题:
问答题
Kara attends a university where students study for an average (arithmetic mean) of 13.4 hours per week. How many hours per week does Kara study? (1) The standard deviation of study time at Kara’s school is 2.8. (2) Kara’s study time is one standard deviation away from the mean.