Solve each proportion. Where necessary, round to the nearest tenth.
4/3 = b/21
I know b=28
do I round to the nearest tenth or what?
28 is a whole number, so b = 28.
Your instructions say round where necessary. It's not necessary here.
(4/3)=(b/21) Multiply with 21
21*(4/3)=b
b=(21*4)/3
b=(84/3)
b=28
28=4*7
21=3*7
(28/21)=(4*7)/(3*7)=(4/3)
To solve the proportion 4/3 = b/21, you can cross-multiply.
Cross-multiplying means multiplying the numerator of the first fraction (4) by the denominator of the second fraction (21), and then multiplying the denominator of the first fraction (3) by the numerator of the second fraction (b).
So, cross-multiplying gives you:
4 * 21 = 3 * b
84 = 3b
To solve for b, divide both sides of the equation by 3:
84/3 = 3b/3
28 = b
Since b = 28 is a whole number and not a decimal, there is no need to round to the nearest tenth in this case. The answer is b = 28.