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The two most populous cities and the non-urban region (NUR) of each of three states, Whimshire, Fogglia, and Humbleset, are assigned Pollution Measures (PMs). These nine PMs are all distinct multiples of 10, ranging from 10 to 90. The six cities in increasing order of their PMs are: Blusterburg, Noodleton, Splutterville, Quackford, Mumpypore, Zingaloo.

The Pollution Index (PI) of a state is a weighted average of the PMs of its NUR and cities, with a weight of 50% for the NUR, and 25% each for its two cities.

There is only one pair of an NUR and a city (considering all cities and all NURs) where the PM of the NUR is greater than that of the city. That NUR and the city both belong to Humbleset.

The PIs of all three states are distinct integers, with Humbleset and Fogglia having the highest and the lowest PI respectively.

What is the PI of Fogglia?

Entered answer:

Solution

✅ Correct Answer: 35
Slide 1/7

We track two linked tables.

Table A lists the six cities with their Pollution Measure (PM) and the state each belongs to.

Table B lists the three states with the PM of their non-urban region (NUR) and their Pollution Index (PI).

CityPMState
Blusterburg
Noodleton
Splutterville
Quackford
Mumpypore
Zingaloo
StateNUR PMPI
Whimshire
Fogglia
Humbleset

There are 99 entities (66 cities + 3+\ 3 NURs) sharing 99 distinct PMs:

{10,20,30,40,50,60,70,80,90}\{10,20,30,40,50,60,70,80,90\}.

The six cities take six of these values; the three NURs take the remaining three.

The given PM order of the cities is

Blusterburg<Noodleton<Splutterville<Quackford<Mumpypore<Zingaloo\text{Blusterburg} < \text{Noodleton} < \text{Splutterville} < \text{Quackford} < \text{Mumpypore} < \text{Zingaloo}.

Each PI is

PI=0.5×(NUR PM)+0.25×(city1)+0.25×(city2)\text{PI} = 0.5\times(\text{NUR PM}) + 0.25\times(\text{city}_1) + 0.25\times(\text{city}_2).

Goal: find every PM, every state assignment, and the three PIs.

CityPMState
Blusterburg30
Noodleton50
Splutterville60
Quackford70
Mumpypore80
Zingaloo90
StateNUR PMPI
Whimshire
Fogglia
Humbleset

All six city PMs are filled from the single NUR>>city rule.

Let the cities in increasing order be c1<c2<⋯<c6c_1<c_2<\dots<c_6 and the NURs be n1<n2<n3n_1<n_2<n_3.

The number of (NUR, city) pairs with NUR >> city equals, for each NUR, the count of cities below it, summed up. This total must be 11.


If two or more NURs were above the smallest city c1c_1, the total would be ≥2\ge 2.

If no NUR were above c1c_1, the total would be 00.

So exactly one NUR lies above c1c_1, and it must lie below c2c_2 (otherwise it would exceed ≥2\ge 2 cities).

The ordering of all nine values is therefore forced:

n1<n2<c1<n3<c2<c3<c4<c5<c6n_1<n_2<c_1<n_3<c_2<c_3<c_4<c_5<c_6.

Mapping to 10,…,9010,\dots,90:

n1=10, n2=20, c1=30, n3=40, c2=50, c3=60, c4=70, c5=80, c6=90n_1=10,\ n_2=20,\ c_1=30,\ n_3=40,\ c_2=50,\ c_3=60,\ c_4=70,\ c_5=80,\ c_6=90.

So the cities are

Blusterburg=30, Noodleton=50, Splutterville=60, Quackford=70, Mumpypore=80, Zingaloo=90\text{Blusterburg}=30,\ \text{Noodleton}=50,\ \text{Splutterville}=60,\ \text{Quackford}=70,\ \text{Mumpypore}=80,\ \text{Zingaloo}=90,

and the three NUR PMs are {10,20,40}\{10,20,40\}.

CityPMState
Blusterburg30Humbleset
Noodleton50
Splutterville60
Quackford70
Mumpypore80
Zingaloo90
StateNUR PMPI
Whimshire
Fogglia
Humbleset40

Blusterburg is assigned to Humbleset, and Humbleset's NUR PM is set to 4040.

The only pair with NUR >> city is n3=40n_3=40 over c1=30c_1=30, i.e. over Blusterburg.

This NUR and this city both belong to Humbleset.

So Humbleset's NUR PM =40=40, and Blusterburg (3030) is one of Humbleset's two cities.

The remaining NUR PMs {10,20}\{10,20\} belong to Whimshire and Fogglia, in some order.

CityPMState
Blusterburg30Humbleset
Noodleton50
Splutterville60W/F
Quackford70
Mumpypore80W/F
Zingaloo90
StateNUR PMPI
Whimshire
Fogglia
Humbleset40

Splutterville and Mumpypore are pinned to the same state, which is either Whimshire or Fogglia (marked W/F).

Since 0.5×NUR0.5\times\text{NUR} is an integer for every NUR∈{10,20,40}\text{NUR}\in\{10,20,40\}, a PI is an integer only when

0.25×(city1+city2)0.25\times(\text{city}_1+\text{city}_2) is an integer,

i.e. the two city PMs of a state sum to a multiple of 44.


City PMs modulo 44:

60≡0, 80≡060\equiv 0,\ 80\equiv 0, and 30,50,70,90≡230,50,70,90\equiv 2.

A pair sums to a multiple of 44 only if both are ≡0\equiv 0 or both are ≡2\equiv 2.

Only 6060 and 8080 are ≡0\equiv 0, so they must be paired together.

Thus one state's cities are Splutterville (6060) and Mumpypore (8080).

Humbleset already contains 3030 (which is ≡2\equiv 2), so this is not Humbleset.

Hence Splutterville and Mumpypore share Whimshire or Fogglia, and Humbleset's second city is one of {50,70,90}\{50,70,90\}.

CityPMState
Blusterburg30Humbleset
Noodleton50
Splutterville60W/F
Quackford70
Mumpypore80W/F
Zingaloo90Humbleset
StateNUR PMPI
Whimshire
Fogglia
Humbleset4050

Zingaloo is fixed as Humbleset's second city, giving Humbleset PI =50=50.

Let Humbleset ={30,x}=\{30,x\} with x∈{50,70,90}x\in\{50,70,90\}:

PIH=20+0.25(30+x)=27.5+0.25x\text{PI}_H = 20 + 0.25(30+x) = 27.5 + 0.25x,

giving 40, 45, 5040,\ 45,\ 50 for x=50,70,90x=50,70,90.

The {60,80}\{60,80\} state has PI =35+0.5×NUR∈{40,45}= 35 + 0.5\times\text{NUR} \in \{40,45\}.


Humbleset must have the strictly highest PI.

If x=50x=50: PIH=40\text{PI}_H=40, but the {60,80}\{60,80\} state can reach 4545, so Humbleset is not highest. Reject.

If x=70x=70: PIH=45\text{PI}_H=45; the leftover cities form {50,90}\{50,90\} (sum 140140) and {60,80}\{60,80\} (sum 140140), both giving 35+0.5×NUR35+0.5\times\text{NUR}. With NURs 10,2010,20 one of these states becomes 4545, tying Humbleset. Reject.

So x=90x=90: Humbleset ={30,90}==\{30,90\}= Blusterburg, Zingaloo, with

PIH=27.5+22.5=50\text{PI}_H = 27.5 + 22.5 = 50.

CityPMState
Blusterburg30Humbleset
Noodleton50Fogglia
Splutterville60Whimshire
Quackford70Fogglia
Mumpypore80Whimshire
Zingaloo90Humbleset
StateNUR PMPI
Whimshire2045
Fogglia1035
Humbleset4050

Whimshire and Fogglia are completed.

The four remaining cities split as {60,80}\{60,80\} (Splutterville, Mumpypore) and {50,70}\{50,70\} (Noodleton, Quackford), with NURs {10,20}\{10,20\}.

{60,80}:35+0.5×NUR⇒40 (NUR 10) or 45 (NUR 20)\{60,80\}: 35 + 0.5\times\text{NUR} \Rightarrow 40\ (\text{NUR }10)\ \text{or}\ 45\ (\text{NUR }20).

{50,70}:30+0.5×NUR⇒35 (NUR 10) or 40 (NUR 20)\{50,70\}: 30 + 0.5\times\text{NUR} \Rightarrow 35\ (\text{NUR }10)\ \text{or}\ 40\ (\text{NUR }20).

The combination {60,80}+10=40\{60,80\}{+}10=40 and {50,70}+20=40\{50,70\}{+}20=40 gives equal PIs, which is rejected (PIs must be distinct).

So {60,80}\{60,80\} takes NUR 2020 (PI 4545) and {50,70}\{50,70\} takes NUR 1010 (PI 3535).


Fogglia has the lowest PI, so Fogglia ={50,70}=\{50,70\}: Noodleton (5050), Quackford (7070), NUR 1010, PI 3535.

Whimshire ={60,80}=\{60,80\}: Splutterville (6060), Mumpypore (8080), NUR 2020, PI 4545.

CityPMState
Blusterburg30Humbleset
Noodleton50Fogglia
Splutterville60Whimshire
Quackford70Fogglia
Mumpypore80Whimshire
Zingaloo90Humbleset
StateNUR PMPI
Whimshire2045
Fogglia1035
Humbleset4050

Every PM, state and PI is now uniquely determined.

Verification of the constraints:

The only NUR >> city pair is 40>3040 > 30 (Humbleset's NUR over Blusterburg) — exactly one such pair, and both lie in Humbleset.

PIs are 5050 (Humbleset), 4545 (Whimshire), 3535 (Fogglia) — distinct integers, with Humbleset highest and Fogglia lowest.

All nine entities (six cities and three NURs) have a known PM and a known state.


Fogglia (the lowest PI) holds Noodleton (5050) and Quackford (7070) with NUR =10= 10.

PI=0.5×10+0.25×50+0.25×70=5+12.5+17.5=35\text{PI} = 0.5\times10 + 0.25\times50 + 0.25\times70 = 5 + 12.5 + 17.5 = 35.

Answer: 3535.

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