Find Unknown Values in Table | Functional Relevance Homework

[Gustavs1337]

Homework Statement

theres a table x - 1;2;3;u;u;u;u;8
y - 370;160;90;u;24;u;u;u u - unknown value
i have to complete this table with this equation y=(k/x)+b you have to find k and b values

Homework Equations

y=(k/x)+b x is relevant to y x -1 is y -370 and x-2 is y-160 and so on

The Attempt at a Solution

I have tried doing this witha calculator adding all kinds of numbers but with no progress :(.

 

[Ray Vickson]

Homework Statement

theres a table x - 1;2;3;u;u;u;u;8
y - 370;160;90;u;24;u;u;u u - unknown value
i have to complete this table with this equation y=(k/x)+b you have to find k and b values

Homework Equations

y=(k/x)+b x is relevant to y x -1 is y -370 and x-2 is y-160 and so on

The Attempt at a Solution

I have tried doing this witha calculator adding all kinds of numbers but with no progress :(.

Are the 4 u-values in x all the same---a single unknown number---or are they 4 unknown numbers? Are the 3 u-values in y the same or different? Are the u's for x the same or different from the u's for y? Do you want an exact fit, or do you want a "best" fit, such a least-squares fit or something similar?

 

[Gustavs1337]

Are the 4 u-values in x all the same---a single unknown number---or are they 4 unknown numbers? Are the 3 u-values in y the same or different? Are the u's for x the same or different from the u's for y? Do you want an exact fit, or do you want a "best" fit, such a least-squares fit or something similar?

the ones in y are different, but i believe that the ones in x might be the same, because 1;2;3 right and the last is 8 not any other number. oh and yea i guess its exact fit if yu mean like 2 or 3 not 2,5 or 3,5

 

[Gustavs1337]

I just figured out something but I am not sure, if k is 420 and b is -50 then it goes correctly by the table but it gets wrong at the 24, because 420/5 -50 is 34 not 24. Can it be a mistake in the table or is there smth I am mistaken in ?

 

[haruspex]

I just figured out something but I am not sure, if k is 420 and b is -50 then it goes correctly by the table but it gets wrong at the 24, because 420/5 -50 is 34 not 24. Can it be a mistake in the table or is there smth I am mistaken in ?

What makes you think x is 5 there?

 

[Gustavs1337]

What makes you think x is 5 there?

Well its mostly because the x-8 is in the end so i thought that the missing x'es were [4;7], but now i think it might not be true because the results don't match. I don't want to believe that there's a mistake in the table tho. I also thought that why are the x'es unknown if it were from 1 to 8, so i think there is some kind of secret or something that i do not know

 

[haruspex]

Well its mostly because the x-8 is in the end so i thought that the missing x'es were [4;7], but now i think it might not be true because the results don't match. I don't want to believe that there's a mistake in the table tho. I also thought that why are the x'es unknown if it were from 1 to 8, so i think there is some kind of secret or something that i do not know

Just drop the assumption that the missing x values are in arithmetic progression. The first three entries in the table are enough to find k and b. Thereafter it is just a matter of calculating the unknown number (x or y) from the known one.

By the way, the easiest way to find k and b is to consider the product xy. This should equal k+bx, so you can do a straight line fit.

 

[Gustavs1337]

Just drop the assumption that the missing x values are in arithmetic progression. The first three entries in the table are enough to find k and b. Thereafter it is just a matter of calculating the unknown number (x or y) from the known one.

By the way, the easiest way to find k and b is to consider the product xy. This should equal k+bx, so you can do a straight line fit.

so k is 420 and b is -50, the first 3 entries agree with me on this one, but i am not fluid in mathematics in english so i can't understand what you mean, do you mean xy=k+bx, sorry, and also do you think the number 24 fits in the table or is it a mistake ?

 

[haruspex]

do you mean xy=k+bx

Yes.

do you think the number 24 fits in the table

Yes.

 

[Gustavs1337]

Just drop the assumption that the missing x values are in arithmetic progression. The first three entries in the table are enough to find k and b. Thereafter it is just a matter of calculating the unknown number (x or y) from the known one.

By the way, the easiest way to find k and b is to consider the product xy. This should equal k+bx, so you can do a straight line fit.

Yes.

Yes.

so, by my calculations x₅ = 5.68 ?

 

[haruspex]

so, by my calculations x₅ = 5.68 ?

Yes.

 

[SammyS]

so, by my calculations x₅ = 5.68 ?

Well that's close. $\ \frac{210}{37}=5\frac{25}{37}\ .$