5250000 determine the number of significant figures

here are three rules on determining how many significant figures are in a number: Non-zero digits are always significant. Any zeros between two significant digits are significant. A final zero or trailing zeros in the decimal portion ONLY are significant.

3 significant figures

Explanation:

We only count the numbers that aren't zero, which is 3. If the number were instead a decimal then we would count all of the numbers including the zeros since they are after the non-zero numbers

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.