When preparing for a climb, many climbers will measure the air pressure at the highest altitudes to which they will be climbing. why do they do this?

Because even at high altitudes there is still plenty of oxygen for breathing. However, pressure is what drives the oxygen into the blood stream. At lower pressure we aren't able to breath because the pressure is not high enough to get the O2 into the blood.

Explanation:

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.