Chapter 1 - Measurement and Problem Solving - Learning Path Questions and Exercises - Exercises - Page 31: 66

White cells in 5 L of blood $=35 \times 10^{9}$, Platelets in 5 L of blood $=125 \times 10^{10}.$

$1L=1dm^{3}=10^{6} mm^{3}$ $5L=5 \times 10^{6} mm^{3}$ So, white cells in 5 L of blood $=7000 \times 5 \times 10^{6}=35 \times 10^{9}$, platelets in 5 L of blood $=250000 \times 5 \times 10^{6}=125 \times 10^{10}.$