Answer:
the correct answer is C
Step-by-step explanation:
18 girls
Half of the students volunteer
15 don't -- so the other half must be 15 as well making there 30 students in the class.
If 12 are boys, then 30(students in class) - 12 (boys) = 18 girls
Answer:
A Pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm and 96 cm but does not resonate at any wavelengths longer than these. This pipe is:
A. closed at both ends
B. open at one end and closed at one end
C. open at both ends.
D. we cannot tell because we do not know the frequency of the sound.
The right choice is:
B. open at one end and closed at one end
.
Step-by-step explanation:
Given:
Length of the pipe, = 120 cm
Its wavelength = 480 cm
= 160 cm and = 96 cm
We have to find whether the pipe is open,closed or open-closed or none.
Note:
- The fundamental wavelength of a pipe which is open at both ends is 2L.
- The fundamental wavelength of a pipe which is closed at one end and open at another end is 4L.
So,
The fundamental wavelength:
⇒
It seems that the pipe is open at one end and closed at one end.
Now lets check with the subsequent wavelengths.
For one side open and one side closed pipe:
An odd-integer number of quarter wavelength have to fit into the tube of length L.
⇒ ⇒
⇒ ⇒
⇒ ⇒
⇒ ⇒
So the pipe is open at one end and closed at one end
.
Answer:
The equation that represents the population after T years is
Step-by-step explanation:
Population in the year 2018 ( P )= 7,632,819,325
Rate of increase R = 1.09 %
The population after T years is given by the formula
-------- (1)
Where P = population in 2018
R = rate of increase
T = time period
Put the values of P & R in above equation we get
This is the equation that represents the population after T years.
(x + 4) (x - 3)
a = 4
b = -3
a^2 + b^2 = ...
= 4^2 + (-3)^2
= 16 + 9
= 25