Thursday
December 5, 2013

# Posts by Alice

Total # Posts: 500

Math
This is from the actual problem - A consumer product testing lab tested 400 13-watt compact fluorescent light bulbs by turning them all on at once, leaving them on until they burned out, and recording the time-to-failure of each bulb. The test revealed a symmetric and mound-sh...

Math
What is the approximate percentile rank of a lightbulb that failed at 9000 hours if the number of lightbulbs is 400? The number of lightbulbs that lasted between 5400 and 9000 were about 326 lightbulbs. The mean is 7800 and the standard deviation is 1200 My guess was: percenti...

Math
The amount of a monthly electric bill (B, measured in \$) depends on the amount of electricity used that month (E, measured in kWh). A typical public utility charges \$0.12 per kWh for the first 300 kWh used, \$0.17 per kWh for the next 600 kWh used, and \$0.29 per kWh for any exc...

social studies
What is the population of:Nile Valley,Ganges Valley and Eastern China

Math
ah, thanks... i'm only taking "liberal arts math", so have only done a little bit of calculus. how did you get this part? H(.2559) = appr 319.7 H(.744) = appr 312.7

Math
H(t) = 0.013t^2 + 0.81t + 316 + 3.5 sin 2πt Ah, the formula should have an exponent!

Math
The formula should actually be: H(t) = 0.013t2 + 0.81t + 316 + 3.5 sin 2πt

Math
Could someone explain how to find which months during the year the maximum/minimum points occur for this problem occurs? I think it's around May and Oct, but I don't get how to determine that on the graph The National Oceanic and Atmospheric Administration (NOAA) has b...

Math
how did you determine the maximum and the minimum?

Math
NOTE - the formula should be: H(t) = 0.013t^2 + 0.81t + 316 + 3.5 sin 2πt

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