Answer:
B
Step-by-step explanation:
The chances of the first student walking to school is 7/30.
Without replacement, there are 29 students left. Hence the chance of the second student walking to school is 6/29 of the original 7/30 chance.
Find the value of x in each case. Give reasons to justify your solutions!
2 answers:
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48 kilograms of 15 % copper is combined with 72 kilograms of 75 % copper to create 120 kg of a 51% copper alloy
<em><u>Solution:</u></em>
Let "x" be the kilograms of 15 % copper
Then, (120 - x) be the kilograms of 75 % copper
Then, according to question,
"x" kilograms of 15 % copper is combined with (120 - x) kilograms of 75 % copper to create 120 kg of a 51% copper alloy
Thus we frame a equation as:
15 % of x + 75 % of (120 - x) = 51 % of 120
<em><u>Solve the equation for "x"</u></em>
Thus 48 kilograms of 15 % copper used
Then, (120 - x) = (120 - 48) = 72
Thus, 72 kilograms of 75 % copper is used