If a sound is 30 db and its absolute pressure was 66 x 10-9 pa, what must have been the reference pressure?

Given:

I = 30dB

P = 66 × Pa

Solution:

Formula used:

I =           (1)

where,

I = intensity of sound

P = absolute pressure

= reference pressure

Using Eqn (1), we get:

=

= 2.08 × Pa

what was the answer?

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.