Least to greatest: 11/15, 13/30, 0.4

Least to greatest: 11/15, 13/30, 0.4

common denominator is 30:   

$$\textcolor[rgb]{1,0,0}{\frac{11}{15}}*\frac{2}{2}= \frac{22}{30}$$

$$\textcolor[rgb]{1,0,0}{\frac{13}{30} }$$

$$\textcolor[rgb]{1,0,0}{0.4}=\frac{4}{10}*\frac{3}{3}=\frac{12}{30}$$

So least to greatest   $$\underbrace{\frac{12}{30}}_{=0.4}$$ ,  $$\frac{13}{30}$$ , $$\underbrace{\frac{22}{30}}_{=\frac{11}{15} }$$  

To make it easier for you. Try to convert them into the same type of numbers. 

TO make a fraction into a demical, just divide the numerator with the denominator.

$${\frac{{\mathtt{11}}}{{\mathtt{15}}}} = {\mathtt{0.733\: \!333\: \!333\: \!333\: \!333\: \!3}}$$

$$(11 \div 15)$$

$${\frac{{\mathtt{13}}}{{\mathtt{30}}}} = {\mathtt{0.433\: \!333\: \!333\: \!333\: \!333\: \!3}}$$

$$(13 \div 30)$$

And 0.4

So...

It would be 0.4, $${\frac{{\mathtt{13}}}{{\mathtt{30}}}}$$ , $${\frac{{\mathtt{11}}}{{\mathtt{15}}}}$$

Thanks Takahiro, that is a good answer

I'm going to try and look at it a bit differently.

11/15, 13/30, 0.4

now half of 15 is 7.5 so 11/15 is more than a half.  

half of 30 is 15 so 13/30 is just a bit less than a half 

0.4 is less than a half

so the BIGGEST one is 11/15

Now 0.4 is 4/10 and 4/10 of 30 is 3*4=12    so 4/10 = 12/30   

so  0.4 is less than 13/30

so

0.4, 13/30, 11/15

If you have a calculator then Takahiros way is easiest.

but I did mine without a calculator.