Could someone help me out with these questions?

Question

The day is defined as having exactly 24 hours of 60 minutes, and each minute is exactly 60 seconds. The year is 365.24 days long. How many seconds are there in 2 centuries, (where a century is 100 years)? (Enter your answer to 2 significant figures)

An athlete runs the mile in 3 minutes, 55.6 seconds. At the same speed, how many seconds does it take the same athlete to run 1200 m? (1 mile = 1609.3 meters) (enter your answer to 2 significant figures)

A chemist wishes to determine the density of an unknown purple liquid. She constructs a cylindrical aluminum container, whose inside radius measures 0.500 inches, with a height of 4.800 inches. When empty, this cylinder has a mass of 91.257 g. When filled with purple liquid its mass was 252.900 g. What is the density of this liquid, in terms of g/cm3?

Answer 1

1.

(24 hrs./day)(60 min.) = 1440. min/day + 60 min. = 1500. minutes/day

(1500. min./day)(60 sec/min) = 90000. sec/day

(90000 sec./day)(365.24 days/yr.) = 32871600. sec/yr.

(32871600. sec/yr. )(200 yrs.)

= 6.6 x 10^9 sec/2 centuries

#2

(1200 m)/(1609.3 m) = .7456658174 % of a mile

(.7456658174 % of a mile)(235.6 sec/mile)

= 1.9 x 10^2 seconds

#3

(252.900 g)-(91.257 g) = 161.643 g sample of unknown liquid

V = (pi)(r^2)(h)

V = (3.14...)(0.500 in^2)(4.800 in.)

= 3.769911184 in.^3

1 in cubed = 16.387064 centimeters cubed (google)

(3.769911184 in.^3)(16.387064 cm^3) = 61.77777585 cm^3 (volume)

(61.77777585 cm^3)/(161.643 g)

= 0.382 g/cm^3