In your biology class, your final grade is based on several things: a lab score, scores on two major tests, and your score on the final exam. There are 100 points available for each score. However, the lab score is worth 23% of your total grade, each major test is worth 22.5%, and the final exam is worth 32%. Compute the weighted average for the following scores: 96 on the lab, 64 on the first major test, 62 on the second major test, and 69 on the final exam.

72.51

Step-by-step explanation:

Given that :

Lab score % = 23%

Each Major test % = 22.5%

Final exam % = 32%

Score :

Lab score = 96

First Major test = 64

Second major test = 62

Final exam = 69

Hence,

Weighted average = Σ(weight % * score)

Weighted average = Σweight_1*score_1 +.. Weight_n * score_n)

(0.23 * 96) + (0.225 * 64) + (0.225 * 62) + (0.32 * 69) = 72.51

step-by-step explanation:

30% of $420 is 0.30($420) = $126 and $420 + $126 = $546.

or, 130% of $420 is 1.3($420) = $546.

notice that this is not the $600 original list price with which we started.

why doesn't this work?

the method does not work because 30% of $420 is not the same amount as the 30% of $600. it may seem obvious when stated this way, but it is a very common error made on problems of this type. we cannot just use the same percent and get back to the original amount because we are taking that percent of a different value.

to work problems of this type correctly, it is generally best to write an equation for the situation and then solve.

example: since (100% – 30%)(original price) = (sale price)

70% of the   (original price) is $420.

0.7x   = 420

equation image indicator

x = 600

the original cost was $600.

we may also solve this problem using the two-step method. working the problem in two steps requires us to use more algebra skills. we have to know that x = 1x (identity property of multiplicationtext annotation indicator) and that 1x – 0.3x = 0.7x (subtracting like terms). then we solve the problem as follows:

(original price) – 30%(original price) = sale price

x – 0.3x = 420

0.7x = $420

equation image indicator

x = 600

the original cost was $600.  

note that with both of the above methods we do obtain the correct original amount.

example: after a 5% pay raise, hermione is earning $22,680 per year. what was she earning before the pay raise?

105% of (original salary) = current salary

1.05x = 22,680

equation image indicator

x = 21,600

hermione earned $21,600 per year before the pay raise.

this is an example so maybe you will get how to at least do it!

answer: i realy don't get it that much can you me figer it out pleas you

step-by-step explanation: