5 times the sum of 12 and a number is 80 What is the value of the unknown number
1 answer:
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Answer:
1. 45.71 miles
2. 10 miles
3. 89.43 miles
4. 0.79 hr
5. 0.025 hr
Step-by-step explanation:
speed = distance/time
After 4 hrs Beverly was 200 miles from home , however she had spent 0.5hr travelling for 20 miles prior to getting to the highway.
Therefore;
Constant speed before Highway = 20/0.5 = 40 miles/hr
Constant speed at Highway = = 51.43 miles/hr
1. in 1 hr beverly will have travelled;
⇒ (20 miles in 0.5 hr ) + (0.5 hr at speed 51.43 miles/hr)
⇒ 20 + (0.5 x 51.43) = 45.71 miles
2. In 0.25 hr beverly had not reached the highway
⇒ distance = speed x time
⇒ distance = 40 x 0.25 = 10 miles
3. in 1.85 hrs beverly will have travvelld;
⇒ (20 miles in 0.5 hr ) + (1.35 hr at speed 51.43 miles/hr)
⇒ 20 + 69.43 = 89.43 miles
4. Time taken to get to 35 miles
⇒ (20 miles in 0.5 hr ) + (15 miles at speed 51.43 miles/hr)
⇒ 0.5hr + (15/51.43) hr = 0.79 hr
5. Time taken to travel 1 mile
⇒ time = distance / speed = 1 mile / 40 miles/hr
⇒ time = 0.025 hr