xlookup, sumif and trend functions for particle size distribution calculation

Hello everyone!

I am trying to create a worksheet for the particle size distribution of soils from sieve and hydrometer test (geotechnical testing).

As I am bit rusty and not an expert, I have encountered several problems in writing more complex formula and functions and I would greatly appreciate some help.

First problem:
I have tried to use together Xlookup and IFSsum, but I think I did not write the formula and conditions properly.

I have two columns in Sheet 2, Particle Size and Percent, the values in both change for each sample we test.

I need to calculate the sums in % from the second column (percent) for a given interval from the column one (Particle Size) and have them displayed in the second table (Quantity).

Exemple: i need xloookup to search for all values in column two, corresponding for the interval >2 to > or equal 6.3 in column one, and give me the sum of all these values (the ones in column two).
I don't know if I was clear enough..

Second problem:
In Sheet1 I need to calculate the Diameter of particles corresponding to the 10%, 30% and 60% of the total amount. I have written the formula, but I don't know how to tell excel to look in the both columns for the values, so I don't have to do it manually, because this also varies for each sample and its not a fixed cell. And the formula should look for these values from C25:C34 and from L43:L54, and the corresponding percent from E25:E34 and from N43:N54. This should be a value, not a sum.
Exemple: the corresponding particle size diameter for 60% is 16.31

Thank you so much for you help!

Welcome to the forum.

I can't see where you have mocked up the results you are expecting (manually).

Get rid of any merged cells - they will cause you more trouble than they are worth.

Hello AliGW. Thank you so much for taking the time to read my post and check the excel.
The calculations are d10, d30, d60 colored in orange, right under the graphic in sheet 1.
The results from the left table, left column in second sheet, colored in orange. The conditions are the ones in the right column, same table.

I am not sure how to write them. I will try later today to bw more specific.
Thank you.