Express proportions.?

Question

Can someone help me express 675 p.p.b. and 1700 p.p.b. as fractions and then as numbers in scientific notation and show reasoning.

Also what is the percentage change between the two figures above and again please show reasoning.

Thanks very much. I am no good at this sort of thing

Answer 1

Don`t know what p.p.b. is unfortunately.

Fraction
675 / 1700
135 / 340
27 / 68
1 / 4

Standard Form
675 = 6.75 x 10²
1700 = 1.7 x 10³

Percentage Increase
change = 1700 - 675 = 1025
Increase from 675 to 1700 = 1025
% increase = (1025 / 675) x 100%
% increase = 152% (to nearest whole number)

Answer 2

I often use ppm, ppb 10^12?

so 675 ppb is 657e-12 (or 657*10^-12)

or 6.57e-10 in scientific notation

all you have to do is move the decimal point 12 places to the left for the floating point

1700 ppb is the same

ie 1700e-12

or 1.7e-9

% (a-b)/b*100

you need to choose the one as the reference
from which the percentage increase or decrease
can be based

(1700-657)/657*100 = 158.8%

or (657-1700)/1700*100 = -61.4%

note (we can ignore the units in the % calculation as long as both numbers are using the same units, in the above case ppb)