# Tutor profile: Tanya T.

## Questions

### Subject: Basic Math

What 3-digit number has the number 5 as its digit in the tens place and the digit in the hundreds place twice as big as the digit in the ones place?

This question can have multiple correct answers. First, we know that the number has 3 digits and the digit in the middle is 5. So far the number looks like this: a5b The digit in the hundreds place is a and the digit in the ones place is b. Possible choices for a and b: a = 8 and b = 4 a = 6 and b = 3 a = 4 and b = 2 a = 2 and b =1 So the number can be either one of these choices: 854, 653, 452, or 251

### Subject: Basic Chemistry

What is the percentage of oxygen by weight in Zn(H2PO4)2 (259g/mol)?

For this question, we assume that we are given a total of 1 mole of the substance. In such a case, the whole substance's weight is 259g. As we are looking for how much percentage of this 259g is made up of Oxygen (O), we can use a periodic table, which gives us the weight of each element per mol. One Oxygen atom's weight is approximately 16g/mol. Looking at the substance's formula, we see that there are a total of 8 Oxygen atoms in the substance. That means the total weight of the Oxygen in the compound is 16g x 8 = 128g. Now, to find out the total mass percentage of Oxygen, we simply divide 128g by 259g and multiply by 100%. Therefore the answer is (128g / 259g) x100% = 49.4%

### Subject: Biology

How are fingerprints formed and when do they become fully developed?

Fingerprints are the ridges formed on our fingers that are unique to every human being. These fingerprints are formed while we are still in our mother's womb, and the pattern of these prints is influenced by several factors such as genetic makeup, position in the womb and umbilical cord length. Fingerprints are formed in the innermost layer of the epidermis known as basal cell layer and it is the rapid cell growth in this basal cell layer that causes the layer to fold and form unique patterns. A baby has fully developed his or her unique fingerprints by the time they turn 6 months old.

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