Madame Curie had \(1\frac{13}{20}\) kg of radium at the beginning.
Further Explanation
Madame Curie used ²/₅ kg for experiment
Radium left = 1¹/₄ kg
Question:
How much radium did she have at first?
The amount of radium that Madame Curie had at first :
= Radium for experiment+ the amount of radium left
\(\boxed {= \frac{2}{5} + 1\frac{1}{4} }\\\)
we can do the additional if the denominator is the same, if not we need to find a common denominator, in this problem, the common denominator for 5 and 4 is 20, so the equation would be:
we change the mixed fraction into an improper fraction
\(\boxed {=\frac{2}{5} + 1\frac{1}{4} } \\\boxed {=\frac{2}{5} + \frac{5}{4} =( \frac{2 \times4}{5 \times4}) + (\frac{5 \times5}{4 \times5}) } \\\boxed {= \frac{8+25}{20} =\frac{33}{20} = 1\frac{13}{20} }\)
So, at first, Madame Curie had 1\(1\frac{13}{20}\) of radium
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Keywords: mixed fraction, fraction, additional fraction, additional, common denominator, numerator
