I need help in the question, and how does the dilution of 10^-4, when turned pos

Question

I need help in the question, and how does the dilution of 10^-4, when turned positive become 10^5 not sure if it's a typo ,please help

416/2018 The total dilution is: 103x 101 10 Now multiply the 70 colonies with the total dilution BUT it must be positive now since we are going back to figure out the original number. 70 colonies x 10 .0x 10>- this MUST be in scientific notation. Why d microbes in the original concentrated sample. Let's apply this to orange juice. o you need to change the exponent to be positive? Because you are trying to determine the number of Q1. 2pts. If the diluted juice has 209 molecules of fructose/ml and you diluted the juice I can concentrate to 9 cans water (not the normal dilution for OJ) or 1:10 which is 10-l, how many molecules/ml are in the concentrate? Explain the math.

Explanation / Answer

1) no, it is not a typo error.

1 ml + 9 ml = 10 ml .................... 10 times dilution of stock

now add 1 ml from dilution to 9 ml

1 ml + 9 ml = 10 ml .................... 100 times dilution of stock

repeat the dilution

1 ml + 9 ml = 10 ml .................... 1000 times dilution of stock

and

1 ml + 9 ml = 10 ml .................... 10000 times dilution of stock.

so the dilution is 104 but we got 70 cfu after spreading (how much microliter ?). generally, we spread 100 microliters. so the cfu/ml is now 700 cfu/ml.

hence 70* 104 *10 = 7.0 * 106 cfu/ml.

BUT if this is not the case then it is a typo error.

2) as you have mentioned that diluted juice contains 209 molecules of fructose/ml. and it is 1:10 diluted. so the number of fructose molecule/ml in concentrate are 209 * 10 = 2090 molecules of fructose/ml.

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