hielly's maths thread

[Hielly]

hey
im going to post up questions im having difficulties in this thread

provide working out

thanks
+1

[ell]

Using information given:















Substituting x back into the original equations, the first boy has 20 marbles, the second 34, and the third 17.

[bec]

Not sure about this (didn't do spesh) but could the equations be:





You need 252L of the 40% solution and 448L of the 15% solution.

Hope that helps/is correct!

[Hielly]

okay here are some that i need help.

1) an investor received $31 000 interest per annum from a sum of money, with part of it invested 10% and the remainder at 7% simple interest. she found that if she interchanged the amounts she had invested she could increase her return by $1000 per annum. calculate the total amount she had invested

2) a biathlon event involves running and cycling. kim can cycle 30 km/h faster than she can run. if kim spends 48 minutes running and a third as much time again cycling in an event that covers a total distance of 60 km, how fast can she run?

3)solve the following linear equation.
-2(5-x)/8 + 6/7 = 4(x-2)/3


thanks

[Flaming_Arrow]

2.  run = x          cycle = x + 30

where x is the speed

distance = speed * time

 

[Flaming_Arrow]

get a common denominator in one side





cross multiply

[Flaming_Arrow]

Let x be the part invested.
Let y be the simple interest.
















therefore $370,588.24 is total amount she had invested

[Hielly]

hey thanks flaming arrow, for question 2 the answer in the book is 15km/h

[Flaming_Arrow]

hey thanks flaming arrow, for question 2 the answer in the book is 15km/h

but that would mean the total distance is 24km

15 * 48/60 + 45*16/60 = 24km

[Hielly]

hrm yerh the book must have mistaken it. also, the wording for this part is a bit confusing can you please explain this

if kim spends 48 minutes running and a third as much time again cycling in an event that covers a total distance of 60 km

thanks

[Flaming_Arrow]

it means if she spends x time running, she spent x/3 times cycling

[Flaming_Arrow]

hey if we substituted it,
say this is equation 1.
x+x+30=60

thus 2x+3-=60 (1)
lets say x=15 what the book said
then,
15+15+30=60
60=60. correct
pretty sure you have to find 2 equations and then use elimination or substitution method.

that doesn't make sense x is the speed and 60 is the distance so how can x + x + 30 = 60?

distance = speed * time

[Hielly]

jrm was just trying to see of 15 km/h is actually right but nvm. then the book is wrong .

[Flaming_Arrow]

[Flaming_Arrow]

how did you gt to the 6 ?

since they have the same power we times the bases