Question:

I need chemistry/Math help?! please!!?

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A sprinter set a high school record in track and field, running 200.0 in 21.5 . What is the average speed of the sprinter in kilometers per hour?

and

A specific brand of gourmet chocolate candy contains 7.00 of dietary fat in each 22.7- piece. How many kilograms of dietary fat are in a box containing 2.00 of candy?

please and thank you! i can't figure these two out!

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  1. Q1   I assume 200 m in 21.5 seconds

    This is a question to trip you up re getting the units right.

    200 m = 0.2 Km

    21.5 sec = 0.00597 hrs  (21.5/(60x60))

    so we have 0.00597 hrs to run 0.2 Km

    so in 1 hr we run 0.2 / 0.00597 = 33.5 Km / hr

    Q2. We have 7 g of fat in a 22.7 g bit.

    How much in a 2 (is that 2 Kg Box ?) = 2000g

    If it is then we have

    22.7g choc as 7g fat. so we have ratio of

    7/22.7  = X / 2000

    X = 2000 x 7/22.7

    Fat in the box = 616.7 g   Don't eat too many !

    = 0.6167 kg   Always check you give the answer in the units they want.

    Hope this helps.


  2. 21.5----------------> 200.0

    60 ------------------> x

    x= 558.13 meters per minute

    x= 33487.8 meters per hour

    x= 33.4878 Km per hour


  3. ASSUMING your units are these: 200m, 21.5 seconds, 7.00 grams, 22.7 grams, and 2.00kg the answer is below.  With other units these won't be valid, so try to include those next time.  

    I started #1 by asking myself "how many km/h = (200m/21.5s)" (1km/1000m)*(60m/1hr)(60s/1m) = 720000/21500km/h = 7200/215km/h = 1440/43km/h = 33.48km/h

    #2

    ?kg fat = 2.0 lb candy (16oz candy/1 lb candy)*(28.35g candy/oz. candy)*(1000g candy/1 kg candy)*(7g fat/ 22.7 g candy)*(1kg fat/1000 g fat) = 6350.4/22700 kg fat = 0.2798 kg fat

    P.S.  I had #1 wrong at first, sorry!

    P.P.S. Just edited to change the answer for #2 since you said it's 2 lbs, not 2 kg.  Should be right now.  You could've also converted the old answer just by converting from kg to lb.

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