Prep Math question

ShirleyWong

Three boxes of supplies have an average weight of 7kg and a median weight of 9kg. What is the maximum possible weight, in kg, of the lightest box?

a. 1
b. 2
c. 3
d. 4
e. 5

Related to this, if I have 1, 2, 2, what is the median? Thanks.

wswhdlp

is 2

ShirleyWong

the answer is 3. I'm confused too. so what is the median if we have a series of 1, 2, 2 for example?

veralove3271

Sum=7*3=21
the median is 9 meaning A 9 B
A+B=21-9=12

You want to minimize B to maxmize A; in other words, B is at least 9. If B is at least 9, A has to be 12-9=3.

ShirleyWong

so, 3, 9, 9 的median is 9?

veralove3271

Yes; you should read Statistic foundation first.

Any odd set of numbers, the median is always the middle one.
Any even set of  numbers, the median is always the sum of the

middle two divided by 2.

ShirleyWong

多谢。这样这道题就明白了。