You can learn more about yarn weights, below.
Yarn weights are known by many names. Fingering wool is fine, and only thread-weight wool is finer.You can review the chart, below, to see where fingering wool fits into their scale of yarn weights.
It depends on what weight the yarn is. There are charts giving approximate values for common weights such as worsted and fingering, but to find out the exact number you have to measure for yourself or consult the label, if it's a commercial yarn.
The number of plies is independent of the weight or fiber content of the yarn. It is possible to have a single ply super bulky like Brown Sheep's Burly Spun, or something like the 8 ply fingering weight on my sock needles right now. If you want to know the plies in a specific yarn, we'd need to know the brand name and yarn name.
There is no hard and fast number that I could give you as an answer. It all depends on what the yarn is made of, what "weight" the yarn is (sock versus bulky, for example). So, as asked, this isn't really an answerable question--there is too much unknown about your yarn to answer with any certainty. My best suggestion would be to go to the yarn manufacturers website and look there for your answer. Or, go back to where you purchased the yarn, and ask there.
Yarns vary, but generally about 170.
There is approx. 150 yards in 50 grams of WORSTED weight yarn so approx 2250 yards in 750g. That is very approximate as different yarns weigh differently and contain different yard amounts in a skein. If you are asking about fingering, sport or chunky weight, the answer would be different.
The common suggestion is to substitute two strands of sport weight for 1 strand of worsted weight. However, everyone's tension is different. If your pattern has a gauge, I would suggest you crochet a small swatch and see if the gauge matches, using your tension. If it is too large, there are other variations you can try. 1 strand of fingering or sock yarn with 1 strand of sport or DK yarn, for example. Of course, that would necessitate having or buying more yarn.
It will depend on the type of yarn. 225 yards of worsted weight yarn is about 100g, but 225 yards of sock weight yarn is about 25g. What is the yarn type?
In the UK, worsted weight yarn corresponds to 10ply (i.e. heavy DK or light aran yarn)
No, a girl cannot lose weight by fingering. However, with proper diet and exercise, she will be able to lose her desired weight.
Grams is a measurement of weight and yards is a measurement of length so it is hard to say definitively how many yards in any one package. That said, however, I checked one fingering weight yarn and it said 50g is 1 3/4 ounces. You might like to check several different manufacturers to compare.
Your answer depends on the weight of the yarn.Thread weight yarn will weigh less than bulky weight, given 'five balls' of each.