Answer:
Step-by-step explanation:


80 x 4 = 79+81+77+x
320=237 + x
320-237 = x
83=x
so Marianne must score 83 points or higher on her last test
The answer is x equals 2.
Your answer should be 81 for a. I got this result by multiplying 9 by 9.
Given:
Principal = Rs. 2000
Rate of interest = 20% p.a. compounded quarterly.
Time = 1 year
To find:
The compound interest.
Solution:
Formula for amount:

where,
P = Principal
r = Rate of interest
t= Time
n = number of times interest compounded in an year.
Putting P=2000, r=0.2, n=4 and t=1, we get




Now, the compound interest is



Therefore, the compound interest is Rs 431.0125.