Hi,thank you for posting your question here at Brainly.
Probability is a numerical value that represents a fraction of a whole. Since there are 4 samples indicated in row X, then there must be 4 probabilities corresponding to each. The sum of all those probabilities must equal to 1. With this information, we could already find the missing probability.
Summation of P = 1 = 0.40 + 0.20 + 0.20 + x
x = 1 - 0.4 - 0.2 - 0.2
x = 0.2 <-- missing probability
The ratio is 12:16, which, when simplified, is 3:4.
For every three girls, there are four boys.
let's firstly convert the mixed fractions to improper fractions and then get their difference.
![\stackrel{mixed}{8\frac{7}{8}}\implies \cfrac{8\cdot 8+7}{8}\implies \stackrel{improper}{\cfrac{71}{8}} ~\hfill \stackrel{mixed}{6\frac{3}{4}}\implies \cfrac{6\cdot 4+3}{4}\implies \stackrel{improper}{\cfrac{27}{4}} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{71}{8}-\cfrac{27}{4}\implies \cfrac{1(71)~~ -~~2(27)}{\underset{\textit{using this LCD}}{8}}\implies \cfrac{71-54}{8}\implies \cfrac{17}{8}\implies 2\frac{1}{8}](https://tex.z-dn.net/?f=%5Cstackrel%7Bmixed%7D%7B8%5Cfrac%7B7%7D%7B8%7D%7D%5Cimplies%20%5Ccfrac%7B8%5Ccdot%208%2B7%7D%7B8%7D%5Cimplies%20%5Cstackrel%7Bimproper%7D%7B%5Ccfrac%7B71%7D%7B8%7D%7D%20~%5Chfill%20%5Cstackrel%7Bmixed%7D%7B6%5Cfrac%7B3%7D%7B4%7D%7D%5Cimplies%20%5Ccfrac%7B6%5Ccdot%204%2B3%7D%7B4%7D%5Cimplies%20%5Cstackrel%7Bimproper%7D%7B%5Ccfrac%7B27%7D%7B4%7D%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20%5Ccfrac%7B71%7D%7B8%7D-%5Ccfrac%7B27%7D%7B4%7D%5Cimplies%20%5Ccfrac%7B1%2871%29~~%20-~~2%2827%29%7D%7B%5Cunderset%7B%5Ctextit%7Busing%20this%20LCD%7D%7D%7B8%7D%7D%5Cimplies%20%5Ccfrac%7B71-54%7D%7B8%7D%5Cimplies%20%5Ccfrac%7B17%7D%7B8%7D%5Cimplies%202%5Cfrac%7B1%7D%7B8%7D)
Divide both by 2:
2/2= 1
50/2= 25
1:25 would be the ratio, or "A".
I hope this helped!
