## vshiroky one year ago Last week David Wright had a batting average of .350. After the next night's game, Wright had 3 hits in 5 at bats, his average increased to .352. Determine the number of at bats and his Wright has altogether.

1. anonymous

.350 is David's cumulative average.

2. anonymous

If you were to add the 3/5 result to compute the new average, the expression would be

3. vshiroky

I'm not sure what to do..

4. anonymous

Let x be the number of hits before the game, and y be the number of bats before the game.

5. anonymous

Then, you have two equations.

6. anonymous

$\frac{ x }{ y } = .350$

7. anonymous

$\frac{ x+3 }{ y+5 } = .352$

8. anonymous

Batting average = #hits/#bats

9. anonymous

Take the two equations above and solve for x, y.

10. vshiroky

how do i solve x&y?

11. vshiroky

@ganeshie8

12. vshiroky

Part 2: At different times in the season, when David Wright had 3 hits for 5 times at bat, his batting average jumped from .350 to .351, from .350 to .355. Explain why the increase is not the same amount each time.

13. wolf1728

vshiroky - Let's solve the first question okay? (x+3) / (y+5) = .352 we can multiply that x + 3 = .352y + 1.76 and x = .350 y

14. wolf1728

We can rearrange those 2 equations A) x -.352y = -1.24 B) x -350y =0 Can you solve that now?

15. wolf1728

Hint multiply equation B by -1

16. vshiroky

625

17. wolf1728

A) x -.352y = -1.24 Okay, I'LL multiply equation B by -1 B) -x +.350y = 0 Now, add both equations -.002y = -1.24 y = 620

18. wolf1728

x = .350y x = 217

19. vshiroky

20. wolf1728

SO, when the batting average was .350 it consisted of 217 hits for 620 at bats The batting average is computed as: hits / at bats 217 / 620 = .350

21. vshiroky

Do I add the 3 to 217? For the total bats to be 220

22. vshiroky

It wants to know at bat and hits all together I think

23. wolf1728

That would be TOTAL HITS = 220 Then add 5 to the at bats making that equal 625 220 / 625 = 0.352

24. vshiroky

So 845 would be my final answer right? To know at bat and hits together?

25. wolf1728

Now you know the hits and at bats for the .350 average AND the hits and at bats for the .352 average I think that answers the first question WAY up at the top of the page. NO your answer is not 845 please look at the answers again

26. vshiroky

I thought to get the # of times he bat and hit would be added but maybe 405 cause I'd have to minus the 2

27. vshiroky

Am I still way off @wolf1728

28. vshiroky

My phone doesn't load to fast. I had to switch off the laptop sorry

29. wolf1728

Basically, you have to understand how the batting avaerage works. if you have 4 hits for 10 at bats what is your batting avaerage?

30. vshiroky

.4

31. vshiroky

.363636

32. wolf1728

CORRECT or .400 as it is usually reported Now, let's say at your NEXT at bat you do NOT get a hit - can you figure out the batting average then? Basically what is the "hits" what is the "at bats" and what is the average?

33. wolf1728

okay the hits = 4 the at bats = 11 and the avaerage = 4/11 = 0.3636363636 OR .364 as it is usually reported

34. wolf1728

So now do you see how to report the hits and the at bats in the original problem?

35. vshiroky

Hits 220 At bats 625

36. wolf1728

Okay, yes Actually, in the first, part it originally asked for the hits and at bats for the .350 average 217 hits 620 at bats

37. vshiroky

Ok

38. wolf1728

Do you have a little bit better idea now?

39. vshiroky

Yes I think so. Thank you.

40. wolf1728

Okay - glad to have helped out :-)

41. vshiroky

I can't medal from my phone but I will from the computer tomorrow