After charging for LaTeX: \frac{1}{3} of an hour, a phone is at LaTeX: \frac{2}{5} of its full power. A) How long will it take the phone to charge completely? B) Write a multiplication and division equation for this situation.

Find the solution below

Step-by-step explanation:

A) Let the complete power of the phone be 1

If after charging 1/3 of an hour, a phone is at 2/5 of its full power, we can write;

1/3 hr = 2/5 of its full power

To determine the time it will take to phone to charge completely, we will say;

x hr = 1

Divide both expression

(1/3)/x = 2/5

1/3x = 2/5

Cross multiply

1 * 5  = 3x * 2

5 = 6x

x = 6/5

x  = 1.2

Hence it will take 1.2 hour for the phone to charge completely

B) From the expression in A

1/3x = 2/5

Multiply both sides by 3

1/3x * 3= 2/5 * 3

x = 2/5 * 3

Hence the multiplication equation is x = 2/5 * 3

Also divide both sides by 1/3

recall 1/3x = 2/5

1/3x ÷ 1/3 = 2/5÷1/3

x = 2/5÷1/3

Hence the division equation is x = 2/5÷1/3

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step-by-step explanation:

(3rd option) - c