#include <stdio.h>
#include <string.h>

int main(void)
{
    // Get test_case
    int t;
    scanf("%d", &t);

    for (int i = 0; i < t; i++)
    {
        int jenis;
        scanf("%d", &jenis);
        int jumlah[jenis];
        int harga[jenis];
        for (int j = 0; j < jenis; j++)
        {
            scanf("%d", &jumlah[j]);
        }
        for (int j = 0; j < jenis; j++)
        {
            scanf("%d", &harga[j]);
        }

        // urutkan jumlah
        int max_jumlah[jenis];
        memset(max_jumlah, 0, sizeof(int) * jenis);
        int pin;
        for (int j = 0; j < jenis; j++)
        {
            int tmp = 0;
            for (int k = 0; k < jenis; k++)
            {
                if (jumlah[k] > tmp)
                {
                    tmp = jumlah[k];
                    pin = k;
                }
            }
            max_jumlah[j] = tmp;
            jumlah[pin] = 0;
        }

        // urutkan harga
        int max_harga[jenis];
        memset(max_harga, 0, sizeof(int) * jenis);
        for (int j = 0; j < jenis; j++)
        {
            int tmp = 0;
            for (int k = 0; k < jenis; k++)
            {
                if (harga[k] > tmp)
                {
                    tmp = harga[k];
                    pin = k;
                }
            }
            max_harga[j] = tmp;
            harga[pin] = 0;
        }

        int sum = 0;
        for (int j = 0; j < jenis; j++)
        {
            sum += (max_harga[j] * max_jumlah[j]);
        }
        printf("%d\n", sum);
    }
}