Answer:
"statement 1: The number of boys at the school is 
 of the number of girls." is true.
Explanation:
Given:
Ratio of Number of boys to the number of girls = 4 : 5
Total number of students = 270
To find:
Number of boys in terms of number of girls = ?
Solution:
As per given statement, 
Let, Number of boys = 

Let, Number of girls = 

Total number of students = Number of boys + Number of girls = 270

Therefore, number of boys = 4 
 30 = 120
And, number of girls = 5 
 30 = 150
As per Statement 1:
Finding 
 of the number of girls:
 = Number of boys.
Finding 
 of the total number of students:
 = Number of boys.
Number of boys is equal to 
 of total number of students.
So, "statement 1: The number of boys at the school is 
 of the number of girls." is true.