The mean length of six rods is 44.2cm. The mean length of 5 of them is 46cm.How long is the sixth rod?

Question

anonymous · Answer

let sixth rod length be  $l_6$$$\frac{l_1+l_2+...+l_5+l_6}{6}=44.2$$$$\frac{l_1+l_2+...+l_5}{5}=46$$

anonymous · Answer

subistitute the value of  $l_1+l_2+...+l_5$ from second equation in first one to isolate  $l_6$

directrix · Answer

The length of the 6th rod is the total lengths of the 6 rods - the total lengths of the 5 rods which is:

6*44.2 - 5*46 = 35.2 cm for the 6th rod

anonymous · Answer

but how did u know that it is the total?

anonymous · Answer

how did u know the sixth rod is the total length of the sixth rod?

anonymous · Answer

the length of the sixth rod is the total length of all six rods i mean*

directrix · Answer

The average is the total of the rods divided by the number of rods.
So, the average times the number of rods takes you back to the sum of the lengths.

anonymous · Answer

could u explain more??

anonymous · Answer

but theur lengths arent the same ya?

anonymous · Answer

or is it?

directrix · Answer

The average of 3 numbers is 4. What is the sum of the numbers?

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