how do i correctly do these algebra problems that i got marked wrong?

Question

1. An investment of $1500 paid interest of $45 during a certain period. How much interest would an investment of $2000 invested at the same rate for the same length of time pay? Show how you checked your answer, please.


2. In baseball, a player's batting average is the ratio of hits to the number of times he or she has batted. Thus, if the player has an average of.300, it means he or she got 300 hits in 1000 bats. In order to have an average of .300, how many hits would the batter have to get in 400 times at bat? Show how you checked your answer, please.

so far i have 300/1000 = x/400, do i just cross multiply? what do i let x equal?

the teacher requires us to show the details of us checking the answers on the side, after we finish solving the problem.

Answer 1

The first problem is simple. 1500:45 :: 2000:x

x = 2000.45/1500 = 4.45/3 = 180/3 = 60 Dollars

There is no scope for checking the answer but it is right as you can see from the method above.

Second problem is also similar and is simple:

0.3 corresponds to 300 out of 1000 or x out of 400

We got 300 by multiplying 1000 by 0.3

Similarly we get 120 by multiplying 400 by 0.3

300/1000 = x/400

x = 300.400/1000 (cross multiply) = 120 so your approach is OK.

Answer 2

1. you paid an interest of 45$ out of 1500$ right so first you would have to find the percentage of that using this equation:
45/1500=x/100 then you cross multiply the two fractions and get 1500x=4500
then you divide both sides by 1500 so x=3%. then you mulitply 2000 by .03 to get the interest that you paid for the two thousand and remember...this is for a certain amount of time which I don't know but 200 is ten percent so that means that three percent of 2000 is 60$ interest so the whole cost is 2060$ but your interest amount is 60$ only.
Sorry but I don't have time to answer your second Q but I hope that you understand it better now.

Answer 3

1. 45/1500 = .03

.03 * 2000 = 60

2. 300 / 1000 = .300

400 * .300 = 120

Answer 4

1. is a percentage problem
45/1500 = x/2000 cross multiply
1500x= 45 x 2000
1500x = 90000 divide by 1500
x = 60

2. 300/1000 = x/400 cross multiply
1000x = 120000 divide by 1000
x = 120

Answer 5

It says that the integers are consecutive, so as meaning they are next to a minimum of one yet another. Examples could be 8 and 9, 11 and 12, and a pair of and 3. What you probably did replaced into make the two values the comparable. x+x=-29 while it is going to likely be x+(x+a million)=-29 ^ the 2d integer is a million extra advantageous than the previous So, in case you sparkling up, x+x+a million=-29 2x=-28 x=-14 You get x=-14. Your mistake replaced into in making the two values the comparable.

Answer 6

1. $60
If $1500 -------------gives------- $45 interest
Then $2000 -------gives-------- ? interest
Hence interest on $2000 = $((2000*45)/1500)=$60

2.yes you may just cross multiply to get 120 as the answer.

Answer 7

for no.2 u cross multiply and get x=120