Using the formula [tex]d=rt[/tex], which of the following statements is not true?

A. If [tex]r=5[/tex] and [tex]t=3[/tex], then [tex]d=15[/tex].
B. If [tex]r=3[/tex] and [tex]t=5[/tex], then [tex]d=8[/tex].
C. If [tex]r=3[/tex] and [tex]t=4[/tex], then [tex]d=12[/tex].
D. If [tex]r=4[/tex] and [tex]t=2[/tex], then [tex]d=8[/tex].



Answer :

Let's use the formula [tex]\( d = r \times t \)[/tex], where [tex]\( d \)[/tex] is the distance, [tex]\( r \)[/tex] is the rate (or speed), and [tex]\( t \)[/tex] is the time. We'll evaluate each of the given statements to determine their correctness.

### Statement 1:
If [tex]\( r = 5 \)[/tex] and [tex]\( t = 3 \)[/tex], then [tex]\( d = 15 \)[/tex].

Calculating the distance:
[tex]\[ d = r \times t = 5 \times 3 = 15 \][/tex]

This statement is true.

### Statement 2:
If [tex]\( r = 3 \)[/tex] and [tex]\( t = 5 \)[/tex], then [tex]\( d = 8 \)[/tex].

Calculating the distance:
[tex]\[ d = r \times t = 3 \times 5 = 15 \][/tex]

This statement claims that [tex]\( d = 8 \)[/tex], but our calculation shows that [tex]\( d = 15 \)[/tex]. Therefore, this statement is not true.

### Statement 3:
If [tex]\( r = 3 \)[/tex] and [tex]\( t = 4 \)[/tex], then [tex]\( d = 12 \)[/tex].

Calculating the distance:
[tex]\[ d = r \times t = 3 \times 4 = 12 \][/tex]

This statement is true.

### Statement 4:
If [tex]\( r = 4 \)[/tex] and [tex]\( t = 2 \)[/tex], then [tex]\( d = 8 \)[/tex].

Calculating the distance:
[tex]\[ d = r \times t = 4 \times 2 = 8 \][/tex]

This statement is true.

### Conclusion
Based on our calculations, the statement that is not true is:

- If [tex]\( r = 3 \)[/tex] and [tex]\( t = 5 \)[/tex], then [tex]\( d = 8 \)[/tex].

We have verified that the correct distance should be [tex]\( d = 15 \)[/tex], not [tex]\( 8 \)[/tex].