Answer
Area of contact between each tire and ground is $A=4.7566\times10^{-4}m^2=4.7566cm^2$
Work Step by Step
Weight of person $W_{p}=625N$
weight of bike $W_{b}=98N$
Total Weight on Two tires $W=W_{p}+W_{b}=625N+98N$
Total Weight on Two tires $W=723N$
assuming that the weight is equally distributed among the tires, force experienced by each tire will be half of the above weight.
so force on each tire $F=\frac{723}{2}N=361.5N$
Pressure in each tire is given as $P=7.6\times10^{5}Pa=7.6\times10^{5}N/m^2$
so from $P=\frac{F}{A}$
$A=\frac{F}{P}$
so area of contact between each tire and ground is
$A=\frac{361.5N}{7.6\times10^{5}N/m^2}$
$A=47.566\times10^{-5}m^2$
$A=4.7566\times10^{-4}m^2$
since $1cm^2=10^{-4}m^2$
$A=4.7566\times10^{-4}m^2=4.7566cm^2$
