Answer: d. The helicopter rotor will spin 36,000 times in 1 hour
Step-by-step explanation:
Option A is wrong because in 40 minutes the rotor will spin:
= 40 * 600
= 24,000 times
Option B is wrong because we cannot know the number of times the rotor will spin before being lifted off of the ground with the details given.
Option C is wrong because in 3 hours the rotor will spin:
= 600 * 3 * 60 minutes
= 108,000 times
Option D is correct because in 1 hour the rotor will spin:
= 600 * 1 * 60 mins
= 36,000 times
The LCM of 24 and 30 is 120.
I have a feeling I've seen this question before
anyway
A=number of hours that plan A is
B=number of hours that plan B is
so
on wednesday, 7hr
5A and 6B so
5A+6B=7
on thursday, 3 hours
3 of A and 2 of B
3A+2B=3
so we gots
5A+6B=7
3A+2B=3
elimination
eliminate B's
multiply 2nd equation by -3 and add to 1st equation
5A+6B=7
<u>-9A-6B=-9 +</u>
-4A+0B=-2
-4A=-2
divide both sides by -4
A=1/2
A=0.5
sub back
3A+2B=3
3(0.5)+2B=3
1.5+2B=3
minus 1.5 both sides
2B=1.5
divide by 2 both sides
B=0.75
plan A lasts 1/2 hour or 0.5 hour or 30 mins
plan B lasts 3/4 hour or 0.75 hour or 45 mins
400 - 3x = 163
Add 3x to both sides.
400 = 163 + 3x
Subtract 163 to both sides.
237 = 3x
237/3 = 79
20? I’m not for sure maybe look in the book? That’s the answer I got and it was right
