An aircraft has a steady rate of climb of $300 \mathrm{~m} / \mathrm{s}$ at sea level and $150 \mathrm{~m} / \mathrm{s}$ at $2500 \mathrm{~m}$ altitude. The time taken (in sec) for this aircraft to climb from $500 \mathrm{~m}$ altitude to $3000 \mathrm{~m}$ altitude is______________
An aircraft has a steady rate of climb of $300 \mathrm{~m} / \mathrm{s}$ at sea level and $150 \mathrm{~m} / \mathrm{s}$ at $2500 \mathrm{~m}$ altitude. The time taken (in sec) for this aircraft to climb from $500 \mathrm{~m}$ altitude to $3000 \mathrm{~m}$ altitude is______________