Answer:
true
True
False
False
Step-by-step explanation:
a. The problem tells me that for every 3 parts of red paint, I have 8 parts of yellow paint. To find the ratio of 1 part of yellow paint I can write the following statement
For 8 parts of yellow paint ------------ 3 parts of red paint
1 part of yellow paint ------------- x
So 

b, I have the following relationship
3 parts of red paint ----- 8 parts of yellow paint
If I multiply the entire expression by 3 I have left
3 * 3 parts of red paint -------- 8 * 3 parts of yellow paint
So
9 parts of red paint ---------- 24 parts of yellow paint
c.I have the same relationship
3 parts of red paint ----- 8 parts of yellow paint
If I multiply the entire expression by 1/2 I have left
3/2 parts of red paint -------- 8/2 parts of yellow paint
So
3/2 parts of red paint ---------- 4 parts of yellow paint
as 3/2 is different from 10, then the approach is false
d. observing the relation of part a,
For 3 parts of red paint ------------ 8 parts of yellow paint
1 part of red paint ------------- x
So 
that is different than 3/8 parts of yellow paint, then the approach is false