1 hr 18 minutes and 27 seconds hmmm
there are 60 minutes in 1 hr, thus 18 minutes is 18/60 hrs or 0.3hr.
so 1hr 18min is 1.3 hrs
there are 60 seconds in 1 minute and 60 minutes in 1 hr, thus 60*60 seconds in 1hr, or 3600 seconds, so, 27 seconds is just 27/3600 hrs, or 0.0075 hrs.
so, 1.3 hr or 1.3000 hr for that matter plus 0.0075, is just
1.3075 hrs.
a)
so, they covered 26.2 miles in 1.3075 hrs, so the average speed is just 26.2/1.3075, or about 20.0382409177 miles/hr
b)
SA=4pir^2
78.54km^2=SA
78.54=4pir^2
divide both sides by 4
19.635=pir^2
aprox pi=3.14 so divide both sides by 3.14
6.25318=r^2
sqrt both sides
2.50063=r
round
radius=2.5km
this question is flawed in that it gives the wrong units
answer is the option with 2.5 in it
2nd one
X^-n duals: 1/x^n. You cannot have negative exponents so do its inverse to get rid of the negative exponent