To develop this problem we will apply the concepts related to the Doppler effect. The frequency of sound perceive by observer changes from source emitting the sound. The frequency received by observer 
is more than the frequency emitted by the source. The expression to find the frequency received by the person is,
= Frequency of the source
= Speed of sound
= Speed of source
The velocity of the ambulance is
Replacing at the expression to frequency of observer we have,
Therefore the frequency receive by observer is 878Hz
Answer:
An object responds to a force by tending to move in the direction of that force
Explanation:
The inertia of a body can be defined with the help of Newton's second law
F = m a
Where F is the applied force, a is the acceleration of the body and m is the mass
the force and the acceleration are vectors that point in the same direction and m is a scalar constant that relates the two vectors, this scalar constant is called masses and it measures the resistance of the bodies to the change of motion.
From the previous statement we see that the statement that best describes inertia is:
An object responds to force by tending to move in the direction of the force.
Iodine-131 has a half life of 8 days, so half of it is gone every 8 days.
10 grams of iodine-131 is left for 24 days.
At 8 days: 10/2=5 grams left
At 16 days: 5/2=2.5 grams left
At 24 days: 2.5/2=1.25 grams left.
**
Your mistake is that you stopped at 16 days.
