I think u have to divide and u get ur answer hope it helps
Answer:
1.5
Step-by-step explanation:
its 1.5 not 1/5
Answer:

Step-by-step explanation:
The 90th percentile of a normally distributed curve occurs at 1.282 standard deviations. Similarly, the 10th percentile of a normally distributed curve occurs at -1.282 standard deviations.
To find the
percentile for the television weights, use the formula:
, where
is the average of the set,
is some constant relevant to the percentile you're finding, and
is one standard deviation.
As I mentioned previously, 90th percentile occurs at 1.282 standard deviations. The average of the set and one standard deviation is already given. Substitute
,
, and
:

Therefore, the 90th percentile weight is 5.1282 pounds.
Repeat the process for calculating the 10th percentile weight:

The difference between these two weights is
.
If Ian uses 1/20 of the ketchup 4 times, this is equal to 4/20, or

.

can be simplified to

, which means we need to work out

of 12.2

is equivalent to 20%, which as a decimal is 0.2
0.2 x 12.2 = 2.44 - however, this is how much he has
used, and we need to figure out how much is left.
12.2 - 2.44 = 9.76
So, Ian has 9.76 oz remaining :)
To find out the last operation, we must solve the entire problem.
We are given:

Let's simplify the signs so they don't clutter our equation.

We always need to be sure to use PEMDAS. Since there is no expression to solve in parenthesis and no exponents are present, we will move on to multiplication. We can multiply -9 and -6 in the denominator. When we do that, we get:

Next, all you need to do is combine like terms in the numerator and the denominator.

Simplify.

To answer the question, the last operation to be performed when finding the value would be division.