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Zorluk: OrtaHCF and LCM

A logistics manager is packing identical relief kits into crates. When she attempts to pack them in equal batches of 1616, 2424, 3030, or 3636 kits per crate, there are always exactly 88 kits left over. However, if she packs them in batches of exactly 1919 kits per crate, there are zero kits left over. What is the least possible total number of relief kits she could be packing?

Cevap: 2888 kits

Cevap

The least possible total number of relief kits is 2888.
The correct answer is derived by finding the general form of a number that leaves a remainder of 8 when divided by 16, 24, 30, and 36. This form is 720k+8720k + 8. By applying the final condition that the total number must be exactly divisible by 19, we find the smallest valid multiplier is k=4k=4. Substituting this back gives 720(4)+8=2888720(4) + 8 = 2888.

Adım Adım Çözüm

1
Establish the relationship for the total number of kits based on the remainders.
The number of kits, NN, leaves a remainder of 88 when divided by 1616, 2424, 3030, and 3636. Thus, N=LCM(16,24,30,36)×k+8N = \text{LCM}(16, 24, 30, 36) \times k + 8.
Any number that leaves the same remainder when divided by multiple divisors can be expressed as a multiple of their least common multiple plus that remainder.
2
Calculate the least common multiple (LCM) of 1616, 2424, 3030, and 3636.
The prime factorizations are 16=2416 = 2^4, 24=23×324 = 2^3 \times 3, 30=2×3×530 = 2 \times 3 \times 5, and 36=22×3236 = 2^2 \times 3^2. The LCM is the product of the highest powers: 24×32×5=7202^4 \times 3^2 \times 5 = 720.
The LCM is required to find the base repeating cycle for the division condition.
3
Formulate the exact divisibility condition.
Substitute the LCM into the equation to get N=720k+8N = 720k + 8. The problem states NN is exactly divisible by 1919, so (720k+8)0(mod19)(720k + 8) \equiv 0 \pmod{19}.
This applies the second constraint of the problem to find the specific multiplier kk.
4
Simplify the modular arithmetic equation to solve for kk.
Divide 720720 by 1919 to find the remainder: 720=19×37+17720 = 19 \times 37 + 17. Substitute 1717 for 720720 to get (17k+8)0(mod19)(17k + 8) \equiv 0 \pmod{19}. This can be written as (2k+8)0(mod19)(-2k + 8) \equiv 0 \pmod{19}.
Simplifying large numbers using modulo properties makes finding the integer kk manageable.
5
Find the smallest positive integer kk that satisfies the equation.
Solving 2k+8=0-2k + 8 = 0 yields 2k=82k = 8, which means k=4k = 4. Checking: 17(4)+8=68+8=7617(4) + 8 = 68 + 8 = 76, and 76÷19=476 \div 19 = 4, which is exactly divisible.
Finding the smallest valid kk ensures we calculate the least possible total number of kits.
6
Calculate the final total number of kits.
N=720(4)+8=2880+8=2888N = 720(4) + 8 = 2880 + 8 = 2888.
Substituting k=4k = 4 back into the original formula for NN provides the final numerical answer.

Anahtar Kavram

Finding a specific numerical value based on multiple simultaneous divisibility and remainder conditions using Least Common Multiple (LCM) and modular arithmetic.
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