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Algebra Level 1

I am watching a video, which if played at normal speed runs for 45 minutes. If I play the same video at 1.25x speed, then how many minutes will it run?

The answer is 36.

4 solutions

Pranshu Gaba
Apr 30, 2016

Relevant wiki: Fractions - Word Problems

Since the length of the video is constant, its speed is inversely proportional to its running time.

Normally, the video runs for 45 minutes. If it is played at 1.25 times faster than normal, then its running time will reduce by 1.25 times. Hence, it will run for

$\begin{aligned} 45 \div 1.25 & = 45 \div \frac{5}{4} \\ & = 45 \times \frac{4}{5} \\ & = \boxed{36} \text{ minutes} & _\square \end{aligned}$

Interesting.

Ben Freeman - 4 years, 4 months ago

45 - 45*.25= 33.25 its rong soultion , hhhhhhhh but easy question

Patience Patience - 5 years, 1 month ago

$\text {Speed = }\dfrac{\text{Distance}}{\text{Time }} \text{ Type logic , where distance is 45,for speed is 1 and time is 45 min} \\ \text{ now we calculate time for speed=1.25 and distance=45 }$

Sabhrant Sachan - 5 years, 1 month ago

i know solution but thats quickly only

Patience Patience - 5 years, 1 month ago

Kurt Vukas
May 1, 2016

We need to get minutes into seconds. 45*60=2700 If the video is playing at 1.25x then 75 seconds passes in the video for every minute of real time. 2700/75=36

Well done!

Pranshu Gaba - 5 years, 1 month ago

Hannes Camitz
May 8, 2016

80 x 1.25=100 100 x 0.8=80.. Hmm so 45 min times 0.8 equals 36 minutes. I believe it was easier for me because I'm used to 25% taxes and to calculate something to become "taxfree" we simply multiply by 0.8. ;-)

Richard Harris
May 2, 2016

1/1.25 * 45 = 36

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The answer is 36.

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