Question

A certain mountain has an elevation of 19,517ft. In 1916, the glacier on this peak covered 4 acres. By 2004 this glacier had melted to only 1 acre.
a) Assume that this glacier melted at a constant rate each year. Find the yearly rate.
b) Use the anser from part (a) to write a linear equation that gives the acreage A of this glacier t years past 1916.

Answer 1

ok so in 2004-1916 years the glacier melted by 1 acre
can you say what is the rate now ?

Answer 2

Not sure what equation to use to find that rate.

Answer 3

rate -> acres per year

so in (2004-1916) = 88 years you lost 1 acre
so the rate is (1/88) acres per year

Answer 4

I get it now. Easy enough; just needed it broken down..

Answer 5

ok .. can you answer (b) ?

Answer 6

I can not figure it out.

Answer 7

ok now you have the rate 1/88 but it is negative rate .. we are loosing glacier so we will put a minus sign in front of it.
it will be our slope (call it m)
and we have a "point" (t1,A1) = (1916,4)
t for us is the year and A for us is the acres melted
since they want the glacier after past 1916 we might call it 0
so our point is (0,4)

so using in order to get the formula for the linear equation :

A = A1 + m(t-t1)

A(t) = 4 - (1/88) * (t-0)
A(t) = 4 - t/88

here you see that after 88 years (at year 2004) you have A(88) = 3
which is like the data you have.

Answer 8

I thought the slope would have to be used to find the equation to be used. Thanks it is so much easier when broken down into easier to understand terms :)