4.2% means 0.042 .
4.2% more than some amount is 1.042 of it.
Interest compounded annually means that a year after you deposit some money
into your bank account, the bank looks to see how much of your money has been
there for a year, and they add  4.2%  of that into your account.  Another way to 
look at it is that they change the balance in your account, from the amount it was 
a year ago, to  1.042  of that amount. That's right. They just <u>give</u> you free money !
Why that's so good is:  Now the new amount in your account is  1.042  of 
the amount you originally deposited, and after another year, they'll give you
another  4.2%  of <em><u>that</u></em> larger amount. Then you'll have  (1.042)² = about  <em><u>
8.6% more</u></em><em /> than your original deposit, 2 years earlier. 
At the end of any number of years ... call it 't' years ... the amount in your 
account is the amount you deposited, multiplied by  (1.042)^'t' power. 
If you just put some money into this particular bank, and forget about it 
and never touch it, you'll have <em><u>double</u></em> the amount in 17 years.
Now we can go and take care of Rhonda.
She put $3000 into a new account at the the bank, and then she forgot 
about it and never touched it. How much is in that account after 't' years ? 
The amount that's in that account at any time is called the 'balance'.
How much is it after 't' years ?
         <em>  Balance = 3,000 (1.042)^'t' power .</em>
        
             
        
        
        
Step-by-step explanation:
I think no. C is the answer. Please let me know by comment I am wrong or right
 
        
                    
             
        
        
        
Check the picture below.
the triangle is an isosceles, so it has twin legs, and a base bottom.
the twin sides stem from the "vertex", and we know the vertex is 120°, and since the triangle is inscribed in a circle, because the circle is "circumscribing" it, then the base side of the triangle will be the diameter of it.
if we run a perpendicular line to the base from the vertex, we'll split the vertex in two 60° angles, as you see there, giving us a 30-60-90 triangle on each side.
so, anyhow, the rest is just a matter of using the 30-60-90 rule.
that's the diameter, and as you know, the radius is just the length of the base, or half the diameter.
 
        
        
        
The frequency stays the same and the wavelength decreases.