hello all , Can u please help me understand why c) 672 is thr right answear in this one :
156(108)138
260( ? )148
a)135 , b)448 , c)672 , d)158 , e )240
Hello, edendeli!
If that's all that is given, there is no unique answer.
Help me understand why $\displaystyle (c)\;672$ is the right answer:
. . $\displaystyle \begin{array}{c}156(108)138 \\ 260(\;\;?\;\;)148 \end{array}$
. . $\displaystyle (a)\;135 \qquad (b)\;448 \qquad (c)\;672 \qquad (d)\;158 \qquad (e)\;240 $
It doesn't help to say "That's exactly how it's written."
There must be some other clues somewhere . . .
Are those 9-digit numbers? .$\displaystyle \begin{array}{c}156108138 \\ 260abc148 \end{array}$
Are they sets of 3-digit numbers? .$\displaystyle \begin{array}{c}
156,\;(108),\;138 \\ 260,\;(abc),\;(148) \end{array}$
We can only guess at the intent of the problem.
Here's one guess . . .
Suppose the middle number is a function of the other two numbers.
. . That is: .$\displaystyle \begin{Bmatrix}f(156,138) &=& 108 \\ f(260,148) &=& ?\end{Bmatrix} \quad\Rightarrow\quad z\:=\:f(x,y)$
Then there are several brizillion possible functions.
Here's a function that produces answer $\displaystyle (c)\;672$
. . . . . $\displaystyle z \:=\:6(x-y)$
That is, subtract the two outer numbers, and multiply by 6.
But this function produces answer $\displaystyle (a)\;135$
. . $\displaystyle z \;=\;\dfrac{441}{2132}x + \dfrac{45}{82}y $
And this function produces answer $\displaystyle (e)\;240$
. . $\displaystyle z \;=\;\dfrac{714}{533}x - \dfrac{30}{41}y$
Conclusion: The author took too much cough syrup . . .
Hello, eveyone!
I still maintain that the problem is grotesquely silly . . .
Originally Posted by edendeli
That's only because we were given the answer.
. . By the way, how were you told that the answer is (c)?
To make my point, I made up a similar problem
. . without giving you the answer.
Given: .$\displaystyle f(1,2) \,=\,9$
Find: .$\displaystyle f(3,7)$
. . $\displaystyle (a)\;27 \qquad(b)\;28 \qquad (c)\;29 \qquad (d)\;30 \qquad (3)\;31$
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Spoiler:
Hello again ,
I obviously havent made myself clear in my previous thread , first i meant thanks very much for taking your time replying to me , after that i just copied your suggested answear and just wrote that i think thats the right logic that they are looking for me to find ( the one you've given , not like i just found it myself ! ) and i yea i agree with you that is incredibly silly and makes no sense at all ,its from an expample test that includes 5 different moduls - maths , literature,history etc ,the maths one include 10 tasks with few " logical " problems , u only have a minute to asnwear each question as well , .... oh and i have the answeasr after each test so thats how i know its C the right answear !
and again thanks for your help .......