A bill for ` 1,840 is paid in the denominations of ` 50, ` 20 and ` 10 notes. 50 notes in all are used. Consider the following statements:

1. 25 notes of ` 50 are used and the remaining are in the denominations of ` 20 and ` 10.

2. 35 notes of ` 20 are used and the remaining are in the denominations of ` 50 and ` 10.

3. 20 notes of ` 10 are used and the remaining are in the denominations of ` 50 and ` 20.

Which of the above statements are not correct?

The correct option is 1, 2 and 3.

Let us analyze the problem step-by-step to understand why all three statements are incorrect (not correct).

We are given:
Total amount of the bill = 1,840
Total number of notes used = 50
Denominations of notes used = 50, 20, and 10

Let:
x be the number of 50 notes used,
y be the number of 20 notes used, and
z be the number of 10 notes used.

Based on the given conditions, we can set up two system equations:

1) Total number of notes constraint:
$x+y+z=50$

2) Total value constraint:
$50x+20y+10z=1840$

Simplifying the second equation by dividing both sides by 10:
$5x+2y+z=184$

Now, let's analyze each statement one by one.

Statement 1: 25 notes of 50 are used and the remaining are in the denominations of 20 and 10.
If $x=25$:
Substituting $x=25$ in the notes equation:
$25+y+z=50\Rightarrow y+z=25$ (Equation A)
Substituting $x=25$ in the simplified value equation:
$5\left(25\right)+2y+z=184\Rightarrow 125+2y+z=184\Rightarrow 2y+z=59$ (Equation B)

Subtracting Equation A from Equation B:
$(2y+z)-(y+z)=59-25\Rightarrow y=34$

Since the total number of remaining notes is only 25, the number of 20 notes ($y=34$) cannot exceed 25. Thus, Statement 1 is not correct.

Statement 2: 35 notes of 20 are used and the remaining are in the denominations of 50 and 10.
If $y=35$:
Substituting $y=35$ in the notes equation:
$x+35+z=50\Rightarrow x+z=15$ (Equation C)
Substituting $y=35$ in the simplified value equation:
$5x+2\left(35\right)+z=184\Rightarrow 5x+70+z=184\Rightarrow 5x+z=114$ (Equation D)

Subtracting Equation C from Equation D:
$(5x+z)-(x+z)=114-15\Rightarrow 4x=99\Rightarrow x=24.75$

Since the number of notes must be an integer, $x$ cannot be 24.75. Thus, Statement 2 is not correct.

Statement 3: 20 notes of 10 are used and the remaining are in the denominations of 50 and 20.
If $z=20$:
Substituting $z=20$ in the notes equation:
$x+y+20=50\Rightarrow x+y=30$ (Equation E)
Substituting $z=20$ in the simplified value equation:
$5x+2y+20=184\Rightarrow 5x+2y=164$ (Equation F)

From Equation E, we can write $y=30-x$. Substitute this into Equation F:
$5x+2(30-x)=164\Rightarrow 5x+60-2x=164\Rightarrow 3x=104\Rightarrow x=34.67$

Since the number of notes must be an integer, $x$ cannot be 34.67. Thus, Statement 3 is not correct.

Since all statements 1, 2, and 3 are not correct, the correct answer option containing the incorrect statements is "1, 2 and 3".