Answer:
D.
![(4)/(3)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/v06kk866m9eblk3tmf1mug5xdc1z0o4ea5.png)
Explanation:
We have been given that a bag contains x blue chips and y red chips. The probability of selecting a red chip at random is 3/7. We are asked to find the
.
![\text{Probability}=\frac{\text{Number of favorable outcomes}}{\text{Total number of possible outcomes}}](https://img.qammunity.org/2021/formulas/mathematics/high-school/cv0n5z6f8glwgkuvz04s3mn23lrtm2o0re.png)
![P(\text{Red})=\frac{\text{Number of red chips}}{\text{Total number of chips}}](https://img.qammunity.org/2021/formulas/mathematics/high-school/4ymkj7jdu9079v2nkq3ob4maunrp1udtxy.png)
![P(\text{Red})=(y)/(x+y)](https://img.qammunity.org/2021/formulas/mathematics/high-school/13ccubo5jagc5fsethtip8r4gqqgqr1hye.png)
Since we are told that probability of selecting a red chip at random is 3/7, so red balls are 3 and total balls are 7:
![P(\text{Red})=(3)/(x+3)](https://img.qammunity.org/2021/formulas/mathematics/high-school/ms2m8u89orc4fxg9bujalhsfu32zugeh5a.png)
Since total balls are 7, so we will get:
![x+3=7\\x=4](https://img.qammunity.org/2021/formulas/mathematics/high-school/4b1a1sa2gb4iczpig8xqslny4jtwr4ccb7.png)
Upon substituting
in expression
, we will get:
![(4)/(3)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/v06kk866m9eblk3tmf1mug5xdc1z0o4ea5.png)
Therefore, the value of
is
and option D is the correct choice.