Answer:
The number of doctors recommended flash toothpaste <u>800</u>.
Step-by-step explanation:
Given:
A magazine ad states that 4 out of 7 doctors recommend Flash toothpaste.
Now, to find the numbers of doctors recommended flash toothpaste if 1400 doctors were surveyed.
Let the number of doctors recommended be
.
And the total number of doctors surveyed were 1400.
So, as given 4 out of 7 doctors recommend flash toothpaste.
So, 4 equivalent to 7 =
.
And,
equivalent to 1400 =
.
Thus, we set the proportion and solve by cross multiplication method:

<em>By cross multiplying we get:</em>
<em>Dividing both sides by 7 we get:</em>


Therefore, the number of doctors recommended flash toothpaste 800.