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mkinjp
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A certain hospital normally has 400 working EKG machines. 27 Jan 2007, 21:41
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A certain hospital normally has 400 working EKG machines. After lightning struck the building, some of the machines began to malfunction and were sent for repairs. Eighty percent of these machines were fixed and returned within the week. If the hospital then had 370 working machines, what is the number of machines that malfunctioned?

OA is 150



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A certain hospital normally has 400 working EKG machines. 27 Jan 2007, 23:01
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Try to tell a story:

A certain hospital normally has 400 working EKG machines.
400
After lightning struck the building, some of the machines began to malfunction and were sent for repairs.
400 - X
Eighty percent of these machines were fixed and returned within the week.
400 - X + .80X
If the hospital then had 370 working machines, what is the number of machines that malfunctioned?
400 - X + .80X = 370

Solve
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mkinjp
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A certain hospital normally has 400 working EKG machines. 28 Jan 2007, 15:53
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its language rather than logic ...isn't it .. Thanks
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Yurik79
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A certain hospital normally has 400 working EKG machines. 28 Jan 2007, 23:05
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mkinjp
A certain hospital normally has 400 working EKG machines. After lightning struck the building, some of the machines began to malfunction and were sent for repairs. Eighty percent of these machines were fixed and returned within the week. If the hospital then had 370 working machines, what is the number of machines that malfunctioned?

OA is 150
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My approach
A certain hospital normally has 400 working EKG machines.
400
x machines began to malfunction and were sent for repairs
Eighty percent of these machines were fixed and returned
the hospital then had 370 working machines
0.8x+remainig mashines=370
now 30 mashines not repaired=20% of x
so x=150



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Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
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Thank you for understanding, and happy exploring!