00:01
Hello guys, we're going to answer the question about it.
00:03
And given a formula, we're going to find for the three parts part a, b and c, n if r equals a given number.
00:16
A, we'll close that for part a.
00:24
We asked to find n if r equals 0 .9.
00:30
Our formula is n of r or n equals minus 7 ,000.
00:38
600 log r our r here for part a is 0 .9 so we plug in r in this equation and we get n of 0 .9 equals 7 ,600 log 0 .9 to plug that in your calculator you get 300 and 47 .7 .7 .7 so let's say 348 for part a.
01:26
N of 0 .9 equals 248.
01:30
For part b, we actually find it at n equals r equals, i mean, 0 .3.
01:41
We do the same thing, we plug in 0 .3 into this formula here.
01:45
So n of 0 .3 equals negative 7 ,600, log.
01:53
0 .3, plug down your calculator, you should get 3 ,974...