Answer:
c. observational study
Step-by-step explanation:
<em>Researchers compare the rates of autism for children who did and did not receive the standard measles-mumps-rubella vaccine, to see if the vaccine might be responsible for autism in some children.</em>
This study design in the above scenario is observational study because the researcher are obviously observing whether the vaccine is affecting the children. Note that Observational study is like experiment which attempts to understand the cause and effect relationships on a subject.
Answer:
(3/4) -(1/4)i
Step-by-step explanation:
Your answer is correct.

You add/subtract complex numbers simply by adding/subtracting real parts and imaginary parts.
So, the real part of this sum is the sum of the real parts:

And the imaginary part of this sum is the sum of the imaginary parts:

So, you have

Let the price of flowers in September be x, then (100 + 20)/100 * x = $1.50
120/100 * x = $1.50
1.2x = $1.50
x = $1.50/1.2 = $1.25
The price of flowers in September is $1.25
Total money realised in September = $1.25 x 900 = $1,125
40% earned = 0.4 x $1,125 = $450
Total money realised in October = $1.50 x 700 = $1,050
40% earned = 0.4 x $1,050 = $420
The class earned more money in September and they earned $30 more than in October.
Answer:
2.2
Step-by-step explanation: