Assume the population of a large city like new york city is about 4 × 10^6 people, with about 1.97 people per household. approximately 1 household in 16.1 has a piano. the piano keyboard has about 64 notes (8 octaves) with about 2 strings per note. a piano should be tuned once per year (365.25 days). a piano tuner can tune about 3 pianos per day. and, finally, pianos tuners work 250 days per year. how many pianos tuners are there in new york city?

So here are the given information:

4 x 10^6 people 

1.97 people = 1 household 

16.1 households = 1 piano 

1 piano = 1 tuning/year 

1 tuner = 3 tunings/working day 

1 year = 250  working days 

Multiplying everything: 

4 x 10^6 people x (1 household/1.97 people) x (1 piano/16.1 households) = 126115.33 pianos in NYC 

126115.33 pianos x (1 (tuning/year)/1 piano) x (1 year/250 working days) x (1 working day/3 pianos/tuner) = 168.15 tuners 

Therefore about 168 piano tuners in NYC.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.