To calculate amount accrued after a given period of time we use the compound interest formula: A= P(1+r/100)∧n where A i the amount, P is the principal amount, r is the rate of interest and n is the interest period.
In the first part; A= $ 675.54, r= 1.25% (compounded semi-annually) and n =22 ( 11 years ), hence, 675.54 = P( 1.0125)∧22
= 675.54= 1.314P
P= $ 514.109 , therefore the principal amount was $ 514 (to nearest dollar)
Part 2
principal amount (p)= $ 541, rate (r) = 1.2 % (compounded twice a year thus rate for one half will be 2.4/2) and the interest period (n)= 34 (17 years×2)
Amount= 541 (1.012)∧34
= 541 ×1.5
= $ 811.5
Therefore, the account balance after $ 811.5.
Dog No dog Total
Cat 31 10 41
No cat 24 7 31
Total 55 17 144
I hope this helps you
2a.2a+1.2a-3.2a-3.1
4a^2+2a-6a-3
4a^2-4a-3
The correct answer should 4% because the ratio is 3 out of 75 which would leave 72 non-defective bulbs. So your answer is 4%
