Answer: 1 & 3/8 cup
This is a mixed number with 1 as the whole part, and 3/8 as the fractional part.
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Explanation:
The mixed number 5 & 1/2 converts to the improper fraction 11/2
Use this formula
a & b/c = (a*c+b)/c
to convert from a mixed number to an improper fraction.
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Then we'll divide the 11/2 over 4 to get
(11/2) divide 4 = (11/2)*(1/4) = 11/8
Let's convert that to a mixed number
11/8 = (8+3)/8
11/8 = 8/8 + 3/8
11/8 = 1 + 3/8
11/8 = 1 & 3/8
Each sibling gets one full cup, plus an extra 3/8 of a cup, of frosting.