As children grow, their eustachian tubes move from a parallel position to an angular position, which increases the frequency of during the preschool years

Perceived Sound

Explanation:

The structure of the Eustachian tube changes as someone moves from childhood to adulthood. This is because the of the the change in the size of muscle opening controlling the tube. These changes make it more sensitive to the perceived sound.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form