## anonymous one year ago WILL GIVE MEDAL! Find the value of x such that the data set has the given mean. 3.8, 4.2, 5.3, x; mean 4.8

1. amoodarya

$4.8=\frac{3.8+4.2+5.3+x}{4}$you can find x

2. anonymous

@amoodarya so would it be 3.325?

3. anonymous

@amoodarya x= 3.325?

4. amoodarya

i think so

5. amoodarya

no it is not x=4(4.8)-5.3-4.2-3.8=5.9

6. welshfella

5.9 is correct

7. anonymous

@welshfella could you explain to me how you get 5.9? I'll give you a medal

8. amoodarya

$4.8=\frac{3.8+4.2+5.3+x}{4}\\\frac{4.8}{1}=\frac{3.8+4.2+5.3+x}{4}\\4.8 *1=3.8+4.2+5.3+x\\$

9. welshfella

first you cross multiply 4 * 4.8 = 19.2 so 3.8 + 4.2 + 5.3 + x = 19.2 adding the numbers on the left 13.3 + x = 192 now subtract 13.3 from both sides (this will leave x on its own on left side) 13.3 + x = 19.2 - 13.3 - 13.3 x = 5.9

10. welshfella

cross multiply:- |dw:1433875265692:dw| -

11. anonymous

@welshfella ok thanks I understand now. could you walk me through one more problem? 100, 121, 105, 113, 108, x; mean 112

12. anonymous

@welshfella I just want to make sure im doing it correctly

13. welshfella

set up an equation as before there are 6 numbers altogether so you divide by 6 112 = 100 + 121 + 105 + 103 + 108 + x ----------------------------- x

14. welshfella

sorry - that is 6 in the bottom of the fraction not x

15. anonymous

@welshfella so add all the numbers then divide by 6

16. anonymous

@welshfella so 89.5

17. welshfella

no cross multiply as before ( that is 112 * 6) : - 112*6 = 100 + 121 + 105 + 103 + 108 + x now solve for x in a similar way to the last question

18. anonymous

@welshfella 672

19. welshfella

112*6 = 672 that 's correct so we have 672 = 100 + 121 + 105 + 103 + 108 + x now find x

20. welshfella

now add up those numbers on the right side

21. anonymous

@welshfella 537

22. welshfella

oops its not 103 but 113!! 672 = 100 + 121 + 105 + 113 + 108 + x

23. welshfella

547 because of the 113

24. anonymous

@welshfella oh I see what to do ok thanks

25. welshfella

x + 547 = 672 now subtract 547 from both sides and you have your answer

26. welshfella

x = 672 - 547

27. anonymous

@welshfella x=125

28. welshfella

right - that looks good